Slight earthworks mark the site of a Roman auxiliary fort, part of the Gelligaer military settlement (see NPRN 275863). The earthworks trace a 2.4ha rectangular enclosure measuring 174m north-east to south-west by 128m. This is outlined by a faint bank about 12m wide and up to 0.3m high. Excavations have suggested that the fort was established in the later first century AD and this is supported by its context on the road between Caerphilly and Brecon, although there have been suggestions of an earlier date. It is uncertain how long it was occupied, but it may have been decommissioned between AD 103 and AD 112 when the nearby stone built fort (NPRN 93007) was constructed.

The outine of the fort is similar to that of the stone-walled fort 50m to the south, although the north fort extends further to the north-east. Both follow the same alignment, facing north-east and the track of a ditch encountered outside the north-west gate of the south fort indicates that they were connected in some way.

Sources: RCAHMW Glamorgan Inventory I.2 (1976), 95-8 [737]
Webster in Studia Celtica XXXIX (2005), 9-15

John Wiles, RCAHMW, 12 February 2008