Traces of a stone keep, known as Tomen Castell, crown a rocky outcrop on the edge of the floodplain of the Lledi River and overlooking the mountain road from Conwy to Ardudwy. Excavations in 1962-3 indicated that the keep was roughly 8.8m by 9.5m, with 2.3-2.95m thick walls. Additional defence was provided by a ditch cut at the western foot of the outcrop.

Tomen Castell is thought to one of a small cluster of early stone-built castles constructed in Gwynedd at the end of the twelfth century, together with Castell Aber Ia (Castell Deudraeth) (NPRN 302700), Carn Fadrun (NPRN 95275), Dinas Emrys (NPRN 95284) and Castell Pen-y-garn (NPRN 407747). These were not placed to withstand alien invasion, but were rather an expression of a Prince's power and lordship in the unsettled period following the death of Owain Gwynedd in 1170 and the subsequent division of the county between his sons. The castle pre-dates the nearby Dolwyddelan Castle constructed in the early 13th century (NPRN 95299) and it is probably here rather than Dolwyddelan that Iorwerth ap Owain Gwynedd's son Llywelyn Fawr was born in c.1173

Louise Barker, RCAHMW, 5th June 2008

Sources:
RCAHMW Caernarvonshire Inventory I (1956), 83 No. 238
Jones in Archaeology in Wales 3 (1963), 16 No. 38 and 4 (1964), 17 No. 42