Crug-y-gaer is a small, oval, univallate enclosure located on a moderate, east-facing slope. The position has no particular strength as it is approached easily from all directions. It measures internally 79.5m north-west to south-east by 69m, an area of about 0.43 hectares. It is now defined by a stony bank but in places erosion has revealed the coursed stone make-up of the original rampart, its base between 6m and 6.5m wide near the entrance gap on the south-east. On the north and north-east the rampart has been reduced to an outward-facing scarp up to 3m high. Elesewhere it survives as a bank of variable dimensions, its inner scarp up to 0.6m high and its outer scarp as low as 0.3m on the north-north-west. A ditch is present in two unconnected lengths on the west and south-west, up to 0.3m deep. It is uncertain whether or not it once surrounded the whole site. The entrance is a simple sunken gap. There are no visible ancient features in the interior.
RCAHMW, Brecknock Inventory vol.I part ii (1986), 117-8.
RCAHMW, 26 January 2016