Excavations at the site of Cerro Portezuelo, located on the lower slopes of a hill in Chimalhuacan, State of México, were begun by George Brainerd in 1954 and continued in 1955, but he died suddenly, before a projected third season could take place. With the exception of a few small structures higher on the hill, no signs of significant structures were visible on the surface. Architectural features revealed through excavation, however, included a platform with associated caches of the Middle Classic period, a platform and a burial area of the Epiclassic period, and a residential complex that appears to have spanned the Early and Late Postclassic periods. This complex included a sunken patio, a freestanding shrine, habitational rooms, and other features. Construction materials included stone, adobe brick, and tepetate.