The medieval castle of Domen Las is represented by a castle mound or motte. This is notable for the way that it is fitted into the natural topography and for the remarkable configuration of its ditch.

The castle faces north-east across the upper Dyfi estuary towards Pennal, the court of the Princes of Gwynedd in Merioneth (see NPRN 302965), and was built in 1156 to counter those Princes' ambitions in Ceredigion. It may then have been the sole castle in Geneu'r-glyn commote, as Castell Gwallter at Llandre is not heard of after 1153 (see NPRN 92234). Domen Las is probably the castle of Abereinion mentioned in 1169 and 1206.

The castle mound is set near the northern tip of an isolated straggling rocky ridge rising from the marshes. It is a circular flat-topped mound roughly 34m in diameter and 5.0m high. It is ditched around except on the south-east, where the ground falls steeply into the marsh. On the west side a rocky ridge serves is co-opted as a counterscarp. On the north side the ditch has the appearance of a regular basin, closed on the east side by a wall of rock pierced by a narrow gap. This could be a pond or cistern, and is surely an original feature.

There are no traces of any further earthworks. The castle mound was probably crowned by a great timber-framed tower and it is likely that a princely hall and associated offices stood nearby. These could have occupied the irregular platform on the northern tip of the spur above the river, although there is a more a more amenable location on the south side of the motte, where a level area is sheltered by the rocky ridge. A little to the south a small bank cuts across the ridge. This was probably a hedge bank and may be comparatively recent.

John Wiles 11.02.08