There are scant remains of Castell Meredydd, a masonry castle traditionally built by Maeredydd Gethin, prince of Gwynllwg, before about 1201. It is possible that the castle went out of use after 1236 although it is mentioned through the earlier fourteenth century.
The castle occupies a ledge on a south-facing hillside. It consisted of a great round tower and another large building, set on conjoined mounds on the south side of a roughly rectangular enclosure or court. The mounds, 4.0-7.0m high, were scarped from an outrcrop set above headlong slopes on the south and ditched towards the court. The great round tower on the eastern mound was about 10m in diameter with 2.0m thick walls. The rectalinear building on the western mound, possible a hall or second tower, would have been up to 18m by 10m. The court is about 56m east-west by 30-56m. It may originally have been walled about. It is now defined by banks and ditches on the east and west and by scarps terraced into rising ground on the north.

Source: Dallimore in the Bulletin of the Board of Celtic Studies 28.3 (1979), 483-8

John Wiles, RCAHMW, 3 August 2007