Two superimposed Roman temporary camps of the type constructed by Roman armies whilst on campaign at located at Y Pigwn. It can be assumed that they mark the passage of two Roman armies at the time of the conquest of the area in the 70s AD. The camps are set about the summit ridge of Y Pigwn on the border between Ystrad Tywi and Brycheiniog, both facing towards the south-west. They are well preserved, although the south-eastern part of the site is much disturbed and obscured by recent tilestone quarrying (NPRN 90450).

Both camps are sub-rectangular and are defined by low spread ramparts with external ditches. The larger, 15ha, camp is about 430m north-east to south-west by 360m, and the smaller, 9.8ha, camp is about 354m east-north-east to west-south-west by 290m. Both show three surviving entrances out of their original four. These all feature internal CLAVICULAE - arcs of rampart behind the entrance gap.

The relationship of the camps' ramparts demonstrates that the larger example is earlier. Both share a common centrepoint, but their orientation is different and they effectively swivel about this central point, where there is a mound, of uncertain age and purpose (NPRN 400450).

Y Pigwn appears to have been a persistently significant place through the Roman period. Here the road between Brecon Gaer and Llandovery (RR62b: NPRN 304405 - NPRN 90448 & 90474) crosses the boundary between Brycheiniog and Ystrad Tywi, and there are a variety of smaller military works (NPRN 304655; 90468; 304654; 308503). A late third century milestone was found at the nearby Blackcock Inn (RIB 2260/1).

Sources: Jones in the Bulletin of the Board of Celtic Studies 23.1 (1968), 100-103
RCAHMW Brecknock Inventory I (1986), 150-153

John Wiles, RCAHMW, 05 June 2007.