A section of the Roman road between Coelbren and Brecon Gaer (RR 622; NPRN 407122).
Two fine stretches of Roman road survive as earthworks either side of the crossing of the Nant-y-Llest. A 280m length of AGGER or causeway is recorded south-west of the stream and a 390m length to the north-east. The causeways are up to 10m wide and 0.5m high.
Trenching reported in 1957 recorded a cambered metalled surface 4.3-4.5m wide on a foundation of larger stones, flanked by 0.5-0.7m wide ditches.
This is part of a 4.0km alignment. The road is next recorded some 850m to the north-east wherea section passes through Blaengwrthyd (NPRN 275632). Some 1.6km to the south-west a poorly preserved section is recorded at Plas-y-fan (NPRN 407127).

Sources: Jones in Archaeologia Cambrensis 106 (1957), 56-63
RCAHMW Brecknock Inventory: Prehistoric & Roman (1986), 161-2

John Wiles 05.12.07