Cas Wilia is an Iron Age enclosure possibly reused as a castle site, situated some 13om west of the Brawdy Brook. Association with two 5th- to 6th- century inscribed stones suggests the enclosure may have been reused as a cemetery during the early medieval period. Two adjacent enclosures have been noted as cropmarks. Cas Wilia II lies some 20m to the south-southeast and Caswilia III, lies some 20m north.
The remaining part of the enclosure measures approximately 200m in diameter, the east side side being occupied by farm buildings which have obliterated two of the banks. The remaining banks are very well defined to the west, with a third bank or counterscarp to the exterior. There is a well-preserved west entrance.

Sources include:

Dyfed Archaeological Trust, 2003, Early Medieval Ecclesiastical Sites Project, Pembrokeshire gazetteer

N Vousden, 10 November 2017