9 Archaeological and cultural heritage web mapping resources: linking the Greek experience with wider research considerations

Abstract

In this paper, we document the current research activities surrounding the mapping of cultural heritage on the web by contextualizing examples from Greek projects and applications within the broader international research landscape. We highlight the benefits of digital mapping for the preservation and promotion of cultural heritage and address specific challenges that call for ongoing and future research. Mapping cultural heritage involves considerable effort from professionals with different backgrounds and can be extensive, as there are no limits to building up digital content. Several opportunities are opening up for expanding the scope of these efforts, foregrounding new questions and research avenues, and creating spin-off applications for diverse audiences. However, there are limitations to the durability of web GIS infrastructures, and their aging in a rapidly changing technological environment can significantly impact the associated content. It is crucial to understand that datafication and content curation go together, and that implementing open data provisions at an early stage can benefit dissemination, support preservation, and create surplus value by enabling third-party and broader audience participation in reusing or repurposing the mapped content.

Introduction

In this paper, we examine the current research environment regarding the mapping of cultural heritage by contextualizing examples from Greek projects within the international research framework. We summarize the opportunities provided by digital mapping for the digitalization and promotion of cultural heritage and identify unresolved challenges that remain as open issues for current and future research in the field. Our survey of the geospatial web aims to loosely categorize a diverse array of applications and examples spanning from late prehistory to the recent past. Additionally, the paper outlines significant milestones in the development of archaeological and cultural heritage web mapping in Greece to situate the current environment within broader research considerations. In this respect, our contribution does not intend to offer an exhaustive historical review of all web mapping applications created to date, nor does it aim to qualify or evaluate the technological solutions employed.

The evolution of digital cartography has advanced rapidly over the last two decades, offering new mapping experiences to users and enhancing data management (Hacıgüzeller 2018), thus contributing to the ‘democratisation of cartography’ (Morrison 1997). In addition, the web and its swift technological advancements have played foundational roles in the provision of web mapping and web geographic information systems (GIS) (Król 2020). Web mapping, the process of designing, implementing, generating, and delivering maps on the World Wide Web (Neumann 2008), not only provides the tools for sharing spatial content but also enables collaborative mapping environments where people can communicate and interact (Hall and Tiropanis 2012). Król (2020) offers a detailed review of the evolution of online mapping, while Veenendaal, Brovelli and Li (2017) distinguish nine web mapping eras, placing the current environment in the ‘Intelligent Web Mapping Era’, where semantic technologies enhance the use, sharing, and visualization of geodata for a broader and more diverse audience.

Cultural heritage maps encompass the mapping of architectural and archaeological heritage, both movable and intangible, within a variety of applications, such as digital libraries, GIS, and location-based cultural tourism applications. In Greece, archaeological maps specifically focus on: a) archaeological monuments or historical places and sites; b) archaeological finds at excavation sites; c) archaeological excavations; and d) archaeological documentation (Koussoulakou et al. 2011). Over the past decade, however, web mapping applications in the archaeological and cultural heritage domain have been expanding their scope. They are now moving beyond typical spatial distributions and data inventories to explore new possibilities for data presentation and exploration. This shift is influenced by related fields, such as spatial history, which employ similar approaches to studying the spatial characteristics of human behaviour, including deep mapping, digital storytelling, and geovisualization (see Earley-Spadoni 2017 for relevant discussions).

Mapping cultural heritage and building the necessary web infrastructure often require significant effort. Heritage data mapping is not simply a digitization procedure but rather a datafication or data building process. This involves transforming existing or static data into new spatially aware information or digital resources that are primarily viewed through the lens of space (and frequently time) (Richards-Rissetto and Landau 2019). Essentially, mapping offers a different data perspective, determining how they can be stored in a database and represented on a map. This usually involves cross-disciplinary teams that combine domain expertise (i.e. knowledge of the past) and technical skills (i.e. digital cartography and web coding). Applications can be developed using various infrastructure solutions and generally demand substantial effort, depending on the range of supported functionalities. Ultimately, after extensive data analysis and GIS experimentation, the effort materializes into a web mapping application. Over the past 25 years, several web resources dedicated to the mapping of archaeology and cultural heritage in Greece have been developed by both domestic and international entities. Some of the most well-known examples are presented in the following section.

Cultural heritage mapping in Greece

Although there are many ways to categorize the web mapping applications and platforms currently available, we opt here for a flexible grouping based on the different objectives or scope of the mappings, rather than on their technological complexity or other sector-specific distinctions. We suggest that such a grouping provides valuable insights, as it focuses on the particularities of the supported content and contextualizes web mapping without forcing into strict distinctions or reducing the apparent technical and thematic variability (Map 9.1).

Map 9.1. 1. Amathountas; 2. Athens; 3. Corinth; 4. Delos; 5. Hermoupoli; 6. Istanbul; 7. Mycenae; 8. Sikyon; 9. Thassos; 10. Thessaloniki; 11. Arcadia; 12. Argolid; 13. Attica; 14. Corinthia; 15. Lasithi; 16. Peloponnese; 17. Thrace.

Geospatial data repositories

A point of reference in Greece for cultural heritage web mapping and an example of one of the earliest digital mapping platforms is Digital Crete. Developed by the Institute of Mediterranean Studies (IMS), it served as a portal for accessing and combining various spatial datasets, including geographic, environmental, cultural heritage, and historical content (Sarris et al. 2008; 2011). Originating from the development of the Digital Archaeological Map of Lasithi (Sarris et al. 2002), the platform went through successive stages of upgrades and data integrations, to the point of covering multiple aspects of the island’s physical and cultural heritage. Digital Crete was a pioneering and influential project, setting a precedent for future efforts in the field of cultural heritage web mapping. By integrating various data sources and presenting them in an accessible online format, it demonstrated the potential for these tools to combine and promote cultural heritage content to a wider audience.

Archaeological Cadastre stands out as the most significant project of the past decade in mapping the country’s cultural heritage. Initiated by the Directorate for the Management of the National Archive of Monuments (DNAM), this ambitious project set out to map all designated archaeological sites and monuments in Greece alongside the properties managed or owned by the Greek Ministry of Culture. Following subsequent development cycles, a web GIS portal was launched in 2022, now offering thematic and geospatial information on 3,400 designated archaeological or historical sites, 844 protection zones, and 17,000 monuments (Fig. 9.1). Content can be filtered by basic chronological periods or resource type. The portal adopts the Linked Open Data approach, by providing stable uniform resource identifiers and downloadable spatial data for each site or monument.

Fig. 9.1. The Archaeological Cadastre platform. The designated archaeological protection Zone A at the Kastri-Chalandriani archaeological site is highlighted. The geometry of the area can be exported as a series of vertices or a polygon shapefile. Site information is included in the respective entry form. Screenshot capture by authors on 10 May 2024. © DNAM.

Web mapping outputs have also been produced as part of the dissemination deliverables of research projects. Examples include Aristeia , which included a web map for archaeological data from the Early Iron Age and the early Archaic period by the University of Thessaly (UTH) (Mazarakis Ainian 2017) (Fig. 9.2), and IGEAN, which created a resource for the Neolithic archaeological sites in Thessaly by the IMS (Sarris et al. 2017). Similar resources have been created for the projects ARENA and AtticPot by the ATHENA Research Centre, examining the archaeology of the northern Aegean with a special focus on the area of Thrace. The former provides a compilation of archaeological research corpora by location, while the latter documents particular aspects of material culture, such as the distribution of Attic paint pottery between the sixth and the fourth century BC (Tsiafaki and Michailidou 2018; Tsiafaki et al. 2022). The EfA offers several online geospatial resources using different mapping platforms and technologies. These include interactive maps for the projects OtHeritages, Église et État à la fin du XIX en Grèce, Cartographier la mémoire, and Frankika or the web GIS platform for the project l’Armee d’Orient.

Fig. 9.2. The web map of the Aristeia project. Archaeological sites in the town of Argos. Different types of sites are shown with different colours. Onscreen selection opens up the catalogue form for each site. Screenshot capture by authors on 10 May 2024. © Aristeia.

In many cases, linking repository entries with a web map provides spatial access to stored content, and as such it is a solution often employed by libraries and archives to enhance the findability of their geospatial content. For instance, the British School at Athens (BSA) Digital Collections offer such facilities to explore their map and aerial photography assets, as well as research records like the Archaeological Survey of the Knossos Area or the Byzantine Research Fund Archive for Byzantine monuments in Greece and other countries.

These types of web applications also support historical studies. The InterMusiG Digital Repository by the National and Kapodistrian University of Athens (NKUA) captures the intercommunal musical history of late Ottoman Istanbul by linking repository data to cartographic displays and searches (Katsianis and Panagiotopoulos 2021). Another example is the Seafaring Lives in Transition (SeaLiT) project by the IMS, which uses ship logbook data to map sea routes travelled by merchant ships in the nineteenth and twentieth centuries (Petrakis et al. 2021). Both projects have incorporated semantic modelling using the CIDOC-CRM ecosystem of models, so as to create meaningful data structures fostering interoperability or even support semantic queries. The project Anavathmis by the Institute of Historical Research of the National Hellenic Research Foundation (IHR-NHRF) set out to develop open-access web resources for its archival material and ongoing research projects. Several web mapping outputs were developed, including the Archive of the Modern Monuments of Athens, which provides a simple but valuable web mapping resource enriched with bibliographic references and visual material, targeting the mapping of buildings in the Greek capital from the start of the Ottoman rule up to the end of the twentieth century. Additionally, the Roman Attica Project by the same institute created web mapping resources for locations linked to coins, people, tombs, roads, buildings, and other constructions from the Roman period in Attica.

Organizations not directly linked to academia have also adopted similar thematic approaches to web mapping. The Dipylon Society for Ancient Topography developed the Mapping Ancient Athens application (Fig. 9.3), which integrates all published material for the capital’s rescue archaeology. Although it deals with excavation data, it is based on a disparate collection of published information. It contains a comprehensive data structure that breaks down information found in excavation reports into individually documented archaeological remains, enabling complex queries based on thematic, chronological, and spatial criteria (Lampraki and Vakkas 2021; Theocharaki et al. 2022). The Athens Western Hills web mapping application includes archival material for studying the historical evolution of the Ηill of the Muses, the Pnyx, and the Nymphs in Athens. It incorporates georeferenced old maps, visual resources, and digitized content on a single cartographic background, providing a cartographic perspective on the diachronic evolution of the respective locations. This combination of archaeological and archival evidence synthesizes and allows the simultaneous investigation of different aspects of both the distant and recent history of the area.

Fig. 9.3. The Mapping Ancient Athens platform. Screenshot capture by authors on 10 May 2024. © Dipylon.

Excavation-based web maps

An important category of web maps includes site-based resources of archaeological remains, produced as part of excavation research projects and often containing complex geometries (e.g. polygons, polylines, 3D meshes, and raster imagery rather than simple point data). Notable examples include the Corinth Computer project (Romano and Stapp 2002) and the Corinth excavations web map by the American School of Classical Studies or the interactive web map of the Sikyon Excavation project, which explores innovative geovisualization methods for presenting and fostering the exploration of excavation records (Lolos, Mousouris and Giannakoula 2023). Recently, EfA has implemented a web GIS infrastructure in which different geospatial data collections from their projects (Delos, Thassos, and Amathountas) are mapped and made openly available to the public (Fig. 9.4). Despite the distinct character of each project, they all utilize a common infrastructure with corresponding geospatial data storage structures. There are several tools for querying layers, links to textual information, or relevant records, as well as different basemaps, including historical maps and aerial imagery. Additionally, 3D viewing functionality has been explored using the Cesium services.

Fig. 9.4. The web GIS of Delos. Search provisions include sector names, which select and zoom to the relevant geometry. Screenshot capture by authors on 10 June 2024. © EfA.

Historical maps

Another set of web mapping applications attempts to bring traditional or old cartographic outputs to the age of the digital humanities. Examples include the maps of the nineteenth-century French Scientific Mission to the Peloponnese through the projects Atlas 1821 and Moree 1829, developed by the IHR-NHRF (Tolias, Gkadolou and El Gedi 2023), or Kitchener’s map in the case of Cyprus (Chalkias et al. 2023). These important pre-industrial landscape-scale mappings are usually complemented with dedicated websites that describe the original map production and the digital mapping process, while sometimes offering an in-depth analysis of different themes of interest. The French Scientific Mission holds particular historical importance, as it represents the first systematic effort to map the cultural heritage of the nascent Greek State and to document their characteristics, condition, and history (Saitas 2011). Similarly, Dipylon’s Karten Von Attica platform transforms the seminal publications of the maps of Attica by E. Curtius and J.A. Kaupert into an interactive mapping platform. This allows the classification of features of interest and their examination on top of modern basemaps (Lampropoulos et al. 2022) or the linking of archaeological information from other sources, such as the DAI sherd collection. In all cases, the digital transformation of historical maps is achieved through the meticulous georeferencing procedures and the subsequent digitization of features of interest.

Geotagging, gazetteers, and text spatialization

Traditional cartographic resources turned to digital data collections are relevant to another category of applications loosely grouped under the umbrella terms of gazetteers and geographical dictionaries or directories. Gazetteers list and describe places, usually over extended geographical areas, and often harvest or incorporate data from existing paper-based or digital sources. Many provide links to each other as a way to enrich their datasets, increase visibility, and foster a new digital ecosystem of place resources (e.g. the Pleiades gazetteer of ancient places or the Trismegistos set of databases about ancient texts). One well-known example is ToposText, a digital tool linking ancient texts with the geographical places they mention. It provides a searchable database of classical literature, helping users explore historical sites through the writings that reference them. The resource, accessible also through mobile versions, targets a wide range of audiences including researchers, students, and travellers interested in the ancient literature and its connections to specific locations. All data are Open Linked Data compatible and available as data collections for bulk downloading. Another significant project is the ArchaeoCosmos portal, developed by the NKUA. It employs a geospatial data infrastructure to collect and integrate disparate project-based archaeological and geographical information within a single data pool covering the wider Eastern Mediterranean region (Kopanias 2021). Recently, in May 2024, Periplus (Fig. 9.5) was launched as part of ArchaeoCosmos, providing a suite of tools for compiling and presenting a web map of Greek toponyms for the entire known ancient world, from Ireland to India, and with a time-range up to the Late Antiquity. It complements Pleiades by adding the ancient Greek toponym scripture and its variations, and by targeting the further addition of toponyms mentioned in ancient Greek literature, such as the ‘Periplus of the Red Sea’. Data entry is part of educational activities at the Department of History and Archaeology and the data is openly provided under the CC BY-NC-SA 4.0 licence. A comparable example is Digital Periegesis, which employs tools for marking and connecting geographic information extracted from the travelling accounts of Pausanias, a well-known traveller from the second century AD, so as to explore place connectivity, itineraries, and geographical storytelling (Foka et al. 2021).

Fig. 9.5. The Periplus Atlas shows different types of toponyms related to geographical features depicted as points (e.g. mountains), lines (e.g. rivers), and polygons (e.g. regions). Screenshot capture by authors on 10 June 2024. © NKUA.

In addition, there are independently developed projects, such as the Mycenaean Atlas Project, which offers a highly detailed and geographically extensive collection of Mycenaean archaeological sites and features. The platform includes a suite of tools for generating data reports, exporting selected datasets, and even performing analytical work on the collected material (Consoli 2021). A further example of individual web mapping initiatives is Kastrologos, an online resource documenting castles, fortresses, towers, and fortification remains in Greece from the fourth to the nineteenth century AD.

Gazetteers with spatial multimedia

Over time, many web inventories have shifted their focus towards providing additional functionalities usually linked to educational content or digital cultural routes. The eCastles platform focuses on mediaeval fortified architecture in the areas of Argolid, Arcadia, and Corinthia. Developed by the Argolid Ephorate of Antiquities, the platform provides an inventory of castles and fortified locations, and is complemented with 3D representation, educational games, interactive applications, and a smartphone application to support onsite visits (Athanasoulis et al. 2015). The Spinalonga: Worlds without walls application developed by the Ephorate of Antiquities of Lasithi follows a similar logic, only this time the web map is confined to the various monuments within the protection zone of the island of Spinalonga. Mobile versions of this application have also been developed for potential travellers.

Community-driven monitoring projects

Another group of applications engages in crowdsourcing or community-based heritage monitoring. The Monuments Under Threat platform (Ganiatsas and Lekakis 2014), launched by the Elliniki Etairia – Society for the Environment and Cultural Heritage (ELLET), introduced an innovative crowdsourcing approach to the recording and conservation of monuments in Greece. It aimed to create an interactive tool for monitoring the condition of Greece’s architectural heritage, allowing for user-generated content to assist in the assessment, prioritization, decision-making, and effective resource management. A similar community-based approach has been employed by the Vault of Industrial Digital Archives (VIDA) for mapping industrial heritage (Fig. 9.6). VIDA’s website facilitates crowdsourced data additions, which are then processed and integrated onto a web map that provides the main public data search and navigation facility to the collected material (Mavroidi 2022). Monumenta, an urban non-profit organization for the protection of the natural and architectural heritage of Greece and Cyprus, has created an extensive dataset documenting the architectural heritage of Athens from the nineteenth and twentieth that aims to raise awareness about the capital’s at-risk architectural legacy. The dataset was originally deployed as a web mapping application, under the title DocAthens, and is presently accessible via the Monument’s main website features detailed records of buildings, including condition assessments, photographs, architectural plans, and historical details, compiled through volunteer-driven documentation projects (Gratsia et al. 2021). One of the most technically successful initiatives has been Hermoupolis Digital Heritage Management (HERMES), which combines an integrated heritage documentation methodology with a data management platform and a public geoportal. Initially targeting the preservation and protection of built heritage in the city of Hermoupolis in Syros (Chatzigrigoriou and Mavrikas 2013), the platform received a Europa Nostra award in 2015. It has since expanded to include both tangible (e.g. listed buildings or sites) and intangible (e.g. stories about buildings or places) cultural heritage aspects and has been upgraded to a digital mobile data collection application linked to a web GIS interface (Chatzigrigoriou et al. 2021). The HERMES methodology has been employed in other projects, such as MouseionTopos, which attempts to highlight the connections between architectural heritage and intangible traditions or craftsmanship within different Aegean island settlements.

Fig. 9.6. The VIDA map interface. Different industry types employ different symbols. Onscreen selection opens the respective industrial monument data form. Screenshot capture by authors on 10 June 2024. © VIDA.

Spatial narratives

A final reference is made here to spatial storytelling (or story maps), a tool that has emerged relatively recently to create web mapping applications, particularly in the cultural heritage domain. Indicative examples are Histories on Map, which comprises three story maps developed in the context of the Archaeological Cadastre project for disseminating information to the wider public about the UNESCO monuments in Greece, the intangible cultural heritage of Greece, and traditional wood shipping in the Aegean Sea.

Common research threads, differences, and challenges

This general overview of past and present web mapping applications in the Greek context attests the numerous efforts made over the years to create cultural heritage geospatial content online using a suite of techniques and solutions. All major stakeholders, including universities (e.g. NKUA, UTH) and research institutes (e.g. IMS, ATHENA, EfA, BSA), public services (e.g. DNAM), societies and private institutions (e.g. Dipylon, ELLET) or communities (e.g. VIDA), as well as independent researchers (e.g. Kastrologos), have developed and continue to develop web resources as part of their research outputs (see Table 9.1). The increasing trend towards undertaking project-based research often leads to the incorporation of web mapping solutions and thematic data collections as project deliverables. Thus, even within the same organization, such as in the case of EfA, geospatial data collections may be employed under different mapping solutions or, to put it differently, the scope of the mapping functionalities of different projects may often require diverging implementations. These individual thematic-based online geospatial data resources are vulnerable to the disrupting of funding and governance policies and susceptible to the challenges related to data siloing described by Huggett, Reilly and Lock (2018). This means that limitations in supporting and maintaining mapping applications, after their development cycle has been completed, impacts their content. The content then essentially becomes unavailable, unless otherwise stored and accessed. In this respect, the entire cultural web mapping environment in Greece follows the fragmentation observed in the broader management of digital archaeological information in Greece (see Tsiafaki and Katsianis 2021). This fragmentation is not solely felt in Greek archaeology and raises severe challenges about the long-term sustainability and growth of web-based digital resources (see country-based contributions in the edited volumes on archaeological data archiving by Jakobsson et al. 2021; 2023). We have tried to identify the areas that we think require further research and coordination.

Table 9.1. List of major web mapping applications included in our review, including information about technology used (not exhaustive), the types of geometries supported (pnt: point, pl: polyline, pol: polygon, grd: grid, 3D: 3D meshes), downloading provisions, access rights, registration requirements, and developer type. NPO: non-profit organization; LOD: linked open data.

Content and functionality expansion

Regardless of potential overlaps or differences in thematic scope and technology, a common challenge across these efforts is that, even when a mapping project is considered finished, the actual completion of a digital mapping may not be. There are always opportunities to expand the spatial and temporal coverage of these mappings by searching for new content outside initial research boundaries, filling gaps across space or time, and including further data at various scales. Likewise, thematic coverage can be expanded using additional sources or media or through the incorporation of content that has been developed in the context of other research efforts or alternative recording channels (e.g. crowdsourcing). Adding new or further data types introduces functionality considerations. For instance, 3D models require 3D visualization provisions, temporal data necessitate temporal navigation tools, while large volumes of information need visualization and infographic solutions to facilitate user comprehension. In this respect, developing a web mapping platform often feels like a never-ending process.

Content expansion may also involve filling in the empty spaces not yet occupied by data, through the incorporation of new sources, data thickening processes or interpolation procedures. Similarly, temporal coverage can be extended by filling in under-represented periods with data. For instance, in the Mapping Ancient Athens platform, the project’s limits in relation to the geographical boundaries of the city of Athens, as well as the variations in data density within these limits, can be easily observed. The chronological distribution of locations shows similar patterns. In both cases, incorporating additional data, whether from outside the project’s spatial boundaries or from new sources such as unpublished archival records from rescue excavations, can significantly expand the informational capacity of the platform (Fig. 9.7). This observation is particularly relevant for gazetteers or thematic inventories, which increasingly rely on crowdsourcing and content curation methods (e.g. ArchaeoCosmos or VIDA) as the only viable means of maintaining and expanding large datasets.

Fig. 9.7. Spatial and temporal coverage of the Mapping Ancient Athens dataset. Screenshot capture by authors on 27 March 2022. © Dipylon.

In the context of the same example, additional content for the platform could be found in existing archives, including both from paper-based or digitized documents. These can include material from the personal archives of the excavators, newspaper reporting, sketches, and photos as well as other audiovisual media. Additionally, 3D content can be integrated into mapping platforms to enhance the understanding of material remains that may have been removed, reburied, or are otherwise obscured (Fig. 9.8).

Fig. 9.8. Types or formats of material that can be linked to web mapping applications: article at Efimeris, 1–2, 25 May 1888; logbook by S. Koumanoudis; drawings by G. Mylonas; photo by I. Travlos; plan by I. Travlos. 3D content: created by authors. Video: excavations at Kotzia Square (Hellenic National AudioVisual Archive). © ASA, Hellenic National AudioVisual Archive.

Obviously, new content formats, such as 3D, may require additional tools to be added or designed for a web mapping interface. For instance, the web GIS resources of EfA or the eCastles platform have provisions in this direction. In the research project Mouseion Topos, platform functionality has been expanded by integrating architectural and geometrical documentation of buildings with the mapping of cultural practices in Aegean traditional settlements into a GIS portal. Through the use of heat maps, the density of historical buildings can be correlated with areas of cultural activity. Additionally, users can access and examine 3D models of buildings (Fig. 9.9), exploring architectural details in their original locations (Chatzigrigoriou et al. 2021).

Fig. 9.9. Functionality expansion in Mouseion Topos through the integration of heatmaps to highlight density of heritage activities and the addition of a 3D viewer to include relevant spatial-specific 3D content. Screenshot capture by authors on 27 March 2022. © Mouseion Topos.

Content integration

The existence of different thematic mapping platforms presents opportunities to combine data, potentially revealing overlaps that can be exploited for other purposes, e.g. land-use planning and management. Larger data pools may be a lot more informative, and they can lead to the discovery of new associations, thus creating added value to each dataset (McKeague 2023). Obviously, combining data from different sources is not straightforward, as there are many difficulties in aligning data that may have been structured in different ways or at varying levels of detail. However, there have been recent calls for the creation of spatial data infrastructures (SDIs) for the historic environment that could render data from different sources as interoperable (McKeague, Corns and Posluschny 2017). An SDI provides a base collection of technologies for spatial data discovery, catering to users and providers in academia, government, commercial, non-profit sectors, and the general public. Creating such infrastructures requires additional work on interoperable data models and appropriate semantic structures for the cultural heritage domain (e.g. INSPIRE or CIDOC-CRM) (Prastacos and Gkadolou 2015). To an extent, however, our review demonstrates that there are existing platforms that have been designed according to these principles, such as the collective management of EfA’s different archaeological fieldwork projects and the interoperability provisions of Mouseion Topos.

To provide an example of the added value potential, the combination of rescue excavation data, listed heritage architecture, and crowdsourced documentation for undesignated pre-war buildings in Athens may provide novel insights into the archaeological potential and the evolution of the modern urban settings. By integrating data from Mapping Ancient Athens, the Archaeological Cadastre project, and Monumenta’s DocAthens platform, potential overlaps or dissociations in space and time may be identified and analysed using standard GIS query tools (Fig. 9.10), allowing the identification of archaeological priority areas in the urban setting.

Fig. 9.10. The potential of bringing content together from multiple platforms. Screenshot capture by authors on 16 October 2024. © DNAM, Dipylon, and Monumenta.

A data integration approach has been employed in the web mapping application Listed Cultural Heritage Sites in the Municipality of Thessaloniki , where data from different providers has been aggregated for monitoring urban cultural heritage and providing statistical information for sustainable development goal (SDG) indicators (Chalkidou et al. 2021). Similar objectives are envisaged for the Single Digital Map, which aims to consolidate critical geographic and regulatory information for spatial planning and development monitoring across urban or regional scales. This map will include data on land use, protection zones, property boundaries, and infrastructure networks, making it accessible to engineers, citizens, and investors to streamline processes, enhance transparency, and support informed decision-making in construction management and property transactions (Ministry of Digital Governance 2021). The Greek Archaeological Cadastre project is considered a key content provider towards that end.

This highlights a crucial point: the informational capacity of mapping platforms offers new opportunities for the research and safeguarding of cultural heritage. In many ways, mapping platforms contain data that, when visualized alongside a broad range of environmental, topographical, or other historical datasets, can display data patterning, bring potential data bias to light, be exploited during development works, or inform heritage monitoring and decision-making. In an example from the city of Patras (Simoni 2016; 2021), the mapping of archaeological and non-archaeological excavation interventions enabled the creation of an archaeological sensitivity map using Voronoi tessellation methods. Not only was it possible to estimate the presence and extent of potential archaeological sites, but also to predict the probable depth of archaeological deposits. Such archaeological predictive models can guide the mitigation of preventive and emergency archaeological interventions, lead to economic value for developers, and facilitate improved decision-making for heritage management services.

Content repurposing

The informational content of cultural heritage mapping efforts can also be harvested and repurposed in other digital cultural applications. The proliferation of mobile technologies in the cultural heritage sector has created novel opportunities for combining existing digital assets with geospatial technologies (Garau and Ilardi 2014). Augmented heritage content is increasingly used in the tourism industry, through the creation of virtual heritage tours and cultural routes (Orlandic and Jaksic-Stojanovic 2021). These enhanced or phygital experiences may attract new audiences through the addition of new layers of information and social interaction. Cultural heritage is made immersive and engaging and possibly more attractive to the digital natives of today (e.g. see Andrade and Dias 2020).

During the development of Mapping Ancient Athens, the initial core geospatial data collection on the ancient walls of Athens was used in the development of Walk the Wall Athens (Fig. 9.11), a bilingual, location-based mobile application for smartphones and tablets (Karagiannopoulou 2021). This application links 35 points of interest (POIs) in a route around the historical centre of Athens. Visitors are guided to approach available POIs, and access information about parts of the wall through text or audio and visual content. In this way, a set of otherwise unrelated places in modern Athens is linked into a cohesive cultural route. Similarly, the original DocAthens platform has been released as an application entitled MONUMENTA – Buildings of Athens, featuring geolocation services that allow the touring of historic neighbourhoods of Athens to visit a significant number of Athenian buildings erected between 1830 and 1940 with photos and their information.

Fig. 9.11. The Walk the Wall mobile application. © Dipylon.

In another example from Thessaloniki, as part of the NEARCH project and the European Cultural Heritage Days event in 2016, seven ‘hidden’ and functionally invisible archaeological sites were selected to showcase the use of new technology for urban heritage. The project Invisible Monuments…Digital Memory utilized QR code posters at the site locations, directing visitors to a website with basic information about each monument (Fig. 9.12). The main purpose of the event was to encourage the public to engage personally with the city’s invisible past, sharing their experiences, stories, and memories through messages and images on social media (Kotsakis and Theodoroudi 2018).

Fig. 9.12. The Invisible Monuments…Digital Memory project. European Cultural Heritage Days 24/9–2/10/2016 NEARCH project, Aristotle University of Thessaloniki. © NEARCH project.

Returning to Athens, the combination of geospatial technologies and 3D modelling has enabled augmented ‘mappings’ of cultural heritage. The Athens Time Walk allows the integration of 3D models into cultural routes, letting users experience 3D townscapes of the past either in an onsite tour or through offsite web browsing. Walk to Plato’s Academy, a recent addition to the number of cultural route mobile apps launched by Dipylon, is a two-hour audiovisual mobile application that offers the opportunity to explore ancient Athens following the path from the Dipylon Gate to Plato’s Academy, using historical information, artwork, and augmented reality functionalities. These examples highlight the rapid adoption of technology in the cultural heritage sector and the potential for reusing data that are compiled as part of mapping applications.

Content curation

In all the examples presented, the crucial element is the actual content and the effort to prepare it. The content can be exploited in many ways, not just within the respective mapping platform. There have been a lot of cultural heritage mapping projects produced for various scales and thematic foci. However, like many digital creations, not all of them remain active. Functionality often diminishes over the years due to the constant evolution of software, internet services, and tools. Web mapping applications frequently suffer from administrative restructures that prevent the continuation of supporting teams. In cases of outsourced development, funding typically ends at the completion of the development cycle and is rarely allocated to infrastructure maintenance or updating. While software applications in the digital realm are destined to become obsolete, their demise can be delayed, and their informational content need not be lost. Securing the content allows for the possibility of revamping old applications into new ones that may be even more relevant and useful than the originals.

As an example, Digital Crete was designed to act as a platform for accessing and combining several spatial datasets, including geographic, environmental, cultural heritage, and historical content. The platform received its latest upgrade before 2010 and remained accessible via the latest ArcGIS server infrastructure until around 2020. Since then, it has been offline, rendering a wealth of material inaccessible. Relaunching the platform with current technologies would likely require re-engineering the entire system and migrating the content. Accordingly, despite having qualified for the 50 most innovative ideas at the European competition ‘@diversity: innovative ideas for cultural and creative sectors in Europe’ in 2013, Monuments Under Threat soon became obsolete, revealing the difficulties in maintaining both the necessary infrastructure and audience base. The Dipylon team faced similar issues when the original Walk the Wall Athens mobile application began encountering software maintenance burdens. Relaunching the application required new outsourced development. In the upgraded version, support and update provisions and content preservation were all prioritized to extend the application’s lifespan, which has since been revamped as a web resource (Dipylon, pers. comm.). During the review of various resources for this article (autumn 2023/spring 2024), several instances were found of broken URLs, of missing or moved content, of mobile versions that had disappeared, and of basemaps that were experiencing performance issues. In this respect, web mapping content should not be viewed as existing solely within the very infrastructure that supports it. Content is valuable and, unless it is made openly available, it should certainly be archived separately, for sharing and reuse.

Although not directly related to digital mapping, we include here a success story when it comes to digital data afterlives. The Parthenon Frieze website was originally developed in 2009 as a Flash-based application that linked all parts of the frieze held in different museums with complementary information and additional educational material, such as simple games. Early content provisions led to the creation of an open-access repository for the informational content of the original application. This structured archiving ensured that, when Flash was discontinued in web browsers, the original application’s demise could be mitigated. Recently, a new cross-platform application using HTML5 has been released. While much of the original functionality, such as the educational games, had to be redeveloped, the repurposing of the existing content made it usable again (Fig. 9.13).

Fig. 9.13. The Parthenon Frieze in subsequent implementation versions. Screenshot capture by authors on subsequent dates between 2018 and 2022. © Acropolis Restoration Service/Acropolis Museum/NDC.

Content dissemination and availability

The considerations discussed above lead to some important realizations. First, cultural heritage mapping can often be a continuous or never-ending process that requires the curation of both content and digital infrastructure. While we typically think of the content as linked to its web platform, this content actually holds great potential for reuse and remixing into new ideas and outputs. However, in many cases the content of cultural heritage mapping platforms is accessible, but practically unavailable or not downloadable for further use. In recent years, there has been a growing advocacy for the open dissemination of cultural heritage data as part of the broader movement of Open Science, which defines a new approach in the scientific process, aiming ‘to make the primary outputs of publicly funded, research results and supporting data, publicly accessible in digital format, with minimal restriction’ (Organisation for Economic Co-operation and Development 2015: 7). A key concept in this context is FAIR data, which stands for data that are findable, accessible, interoperable, and reusable. FAIR data encourage developers to consider data stewardship issues, such as data provenance, semantic interoperability, and data licencing, from the beginning of their mapping endeavours (Wilkinson et al. 2016). Recently, two large European projects have explored the harvesting of geospatial cultural data, furthering these principles and promoting the open sharing and effective reuse of cultural heritage information.

The ARIADNEplus project tried to bring together, in a single searchable aggregator, archaeological data collections from different countries and organizations. Within this project, a group of experts surveyed and registered several online geospatial archaeological data services with the aim of creating an integrated catalogue of services.

The final report of this project indicates the difficulties in integrating geospatial data and identifies several key issues (Novák and Hasil 2021):

• Low awareness of existing standards for geodata exchange and presentation.

• Low levels of spatial data standardization and a persistence of offline storing.

• A focus on building custom web GIS applications to present archaeological data, which do not include provisions for machine-based dissemination or reuse.

• Licencing barriers to sharing and publishing archaeological data.

• The requirement of advanced skills to create and use Open GIS compatible geospatial services.

The last point is particularly related to the lack of geospatial literacy within heritage studies in current higher education curricula (see also Kozina, Ciglič and Spini 2021; Mazagol et al. 2022).

SEADDA comprised a research network of archaeologists and digital specialists working together to secure the future of archaeological data across Europe and beyond. In an effort to survey the reuse potential of available archaeological data and barriers to reuse, a user experience survey was launched, which among other data types targeted geospatial data availability and accessibility. Respondents reviewed data provider platforms and provided feedback on the ease of locating, accessing, and reusing their content. Notable platform limitations included the unavailability of bulk data exporting, constraints on the reusability of available formats, limited search and filtering facilities, or the lack of explicit licencing information. For example, the Archaeological Cadastre allows one to export shapefiles of individual selected entities (e.g. areas of designated archaeological sites) and to print scaled map displays. However, it does not support multiple selections, and relevant thematic information must be downloaded separately (Seaton et al. 2023). In Greece, although steps have been taken towards open data dissemination, the current landscape is far from regularized (Katsianis and Tsiafaki 2024). This is especially true for geospatial data collections, whose open availability (with a few exceptions) falls short of meeting many of the above user criteria. Out of 39 web mapping or web GIS platforms reviewed, 41% retain all copyright of material presented, 36% provide no licencing information, and only 18% adopt some form of creative commons licence. This is reflected in the downloading provisions, where only 10% allow bulk downloading of actual geometries (although another 7.5% declare future steps towards implementing this functionality) (see Table 9.1).

It should be noted that content reuse might not align with the original conception and intentions of the developers. Drawing from our experience as GIS tutors in cultural heritage, we considered the potential to reuse, repurpose, or spatially enhance available data. As part of the Digital Methods for the Humanities postgraduate programme at the Athens University of Economics and Business, we are often in need of geospatial data for educational digital mapping activities. In the past we have employed data from our own projects, as well as data available online (e.g. data from the Antikythera Survey Project have been used for showcasing thematic classification and other geoprocessing functions in the practical context of our course, see Bevan and Conolly 2012; 2014). We have also used cultural content generated by web-based communities (see e.g. Papageorgiou 2016). For instance, photographs published in the Facebook group, Old photographs of Athens, Attica, were georeferenced and re-captured from approximately the same angle in a 2019 MA dissertation to create ‘then’ and ‘now’ comparisons of the urban settings (Nikolou 2019). This example highlights the potential of reusing crowdsourced curated content by simply linking it to its spatial locations (Fig. 9.14).

Fig. 9.14. Reusing content from the Old photos of Athens, Attiki Facebook group to create geolocated content. CC BY 4.0.

Conclusions

To sum up, mapping cultural heritage requires significant effort and coordination from interdisciplinary research and development teams. In Greece, considerable attention has been directed to the creation and dissemination of archaeological, historical, and broader heritage-related geospatial applications. These applications vary widely in their spatial, temporal, or thematic coverage, as well as in their technological choices. This variability is partly related to the gradual adoption of mapping approaches from other fields that has opened up web mapping application scope and usage. Several of the examples presented here are long-term projects that have successfully navigated the challenges of project-based research and the rapid evolution of web mapping technologies by extending their scope in both content and functionality. In this context, curating geospatial web data structures can be a long-term activity, as building digital content is limitless and requires regular, if not constant, curation. However, there are limits to the longevity of web mapping or web GIS infrastructures and, in many cases, when a platform becomes outdated its underlying content is often severely impacted. It is important to recognize that datafication and content curation go together. Implementing open (and linked) data provisions at an early stage can benefit dissemination, foster preservation, and create surplus value by enabling third parties and the broader audience to engage with and use the mapped content. In doing so, several opportunities open up for extending the scope of these efforts, foregrounding new questions and research avenues, and encouraging content reuse by diverse audiences.