Cropmarks at Croes-y-Bryn show a bivallate, broadly rectangular plough-levelled enclosure with maximum dimensions of 56m east-west by 75m north-south. The outer enclosure has broad ditches, rounded corners, slightly bowed-out north and south sides with a slightly curving west side which is pierced by the main gate. The inner enclosure, measuring 45m square, is set concentrically within the southern part of the outer, and has narrower ditches than the outer. The main gate on the west side has a matching gap in both inner and outer enclosures, but with two markedly darker, larger terminals to the ditches on the south side. It is not clear why the ditches on the southern side of the gateway should be much larger and more clearly defined.

The square and rectangular form of this enclosure is not unusual in the context of other plough-levelled Late Iron Age and Romano-British enclosures in south-west Ceredigion. However, its concentric form is more complex than many, and its neat layout and the proximity of a Roman cremation burial may invite speculation as to a Roman date, or even a potential villa enclosure.

At the time of its discovery during RCAHMW aerial reconnaissance in 1995 a house was under construction over the south-east portion of the enclosure which is now prsumably destroyed.

The position of this enclosure is not without significance. It lies 125m generally east of an early medieval inscribed stone - the Corbalengi Stone - which had a Roman cremation deposit at its base (NPRN 304135). It sits alongside an old ridge-top cross-roads but as one of the roads to Penbryn crosses over the enclosure this must post-date the settlement. A possible rectangular feature about 80m to the west of the enclosure has been noted (NPRN 401407).

T. Driver, RCAHMW, May 2015