Maiden Castle, prehistoric fortress, Dorset, S England, near Dorchester. The finest earthwork in the British Isles, c.120 acres (50 hectares) in area, is there. Two sets of large-scale excavations at this site indicate it was first occupied during the Neolithic period (c.2000 B.C.); two concentric ditches define this early, 15.8-acre (6-hectare) occupation. It was then abandoned until the early Iron Age (c.300 B.C.), when an elaborate system of enclosing banks and ditches was built, making it one of the largest hill forts in Europe. It subsequently underwent numerous changes in form and function. It was abandoned c.A.D. 70, shortly after the Roman invasion, and its inhabitants moved to a nearby valley town.