The Roman military settlement at Penydarren is centred on a presumed auxiliary fort enclosure, about 120-150m across, oriented north-north-east to south-south-west on a steep sided ridge above the floor of the Taf valley.

Roman remains were first discovered when Penydarren House (now demolished) was constructed in 1786. Further excavations in 1902-4 (James 1906) examined various parts of the settlement, including the remains of a bathhouse south of the fort. More recent work examined an angle of the fort enclosure (Heywood 1991). The fort itself is estimated to cover an area of around 2.3ha and probably held a garrison of at least 500. The pottery recovered during excavation is consistent with a foundation in the Flavian period and continuing until around AD 140.

Cremations and possible building remains have been found at some distance on the slopes above the fort, suggesting the presence of an extensive settlement under modern houses and gardens.

Sources: James 1906 in Archaeologia Cambrensis 6, 193-203
Jarrett 1969 'The Roman Frontier in Wales', 2nd ed., 106-8
RCAHMW 1976 Glamorganshire Inventory I.2, 84-6
Heywood 1991 in Bulletin of the Board of Celtic Studies 38, 167-90.

John Wiles, RCAHMW, 18 August 2004.