Lying 1¼ miles (2 km) to the southeast of Bonnybridge, Rough Castle is the best preserved of the Antonine forts. The Antonine Wall was built around 143 AD and stretched from Bo'ness on the River Forth to Old Kilpatrick on the River Clyde.
Located immediately to the south of the wall, this fort was relatively small, extending to 0.4 ha (1 acre) in size and enclosed within ditches and a rampart. Gateways were located on each of its four sides, with roadways across the defensive ditches to allow access. An annex was added later to the east. The fort included some substantial stone buildings, including a headquarters, the commander's house and a granary. The foundations of these buildings were located during excavations. Excavations took place in 1902-3, 1932 and 1957-61.
Inscriptions on retrieved artefacts tell us that the fort was the base of some 500 men of the Sixth Cohort of Nervii, an infantry unit recruited from a tribe in North East France.
The area is managed by Historic Environment Scotland on behalf of its owner the National Trust for Scotland.