Archaeological fieldwork in the Forth-Clyde isthmus has been dominated by the World Heritage Monument of the Antonine Wall, the Roman frontier built in the second century a.d. Considerably less attention has been given to the evidence for post-Roman experience of the Wall and how it was remembered (and forgotten) in the subsequent centuries. This paper will briefly summarise historical notices of the Antonine Wall, then consider the archaeological and toponymic evidence for early medieval occupation. The role of the Forth-Clyde isthmus as a political frontier is shown to be less significant to our understanding of this period than the evidence for mobility, memory and the contested legacy of Rome in early medieval Scotland.