Dyserth Castle was a grand stone-built castle constructed by Henry III from 1241 and eventually destroyed by Llywelyn ab Gruffudd in 1263, after seven years of blockade and siege. It is thought to have occupied the site of a later prehistoric style hillfort, occupied into the Roman period. The castle was sometimes known as Castell-y-Garrec or Caer Faelan.
Most of the castle was destoyed by quarrying in the early twentieth century, leaving only the earthworks of the outer court and part of the ditch of the stone castle. Survey and excavations were undertaken prior to the castle's destruction, but there is no way of checking their accuracy. The site and the castle ruins are depicted prior to their destruction on early editions of the Ordnance Survey County series.
The castle occupied the summit of a terrific crag overlooking the Vale of Clwyd. It had a small inner court about 30m by 15-20m with great polygonal towers, including a twin towered gatehouse. This stood within a larger court, perhaps 60-80m across, whose walls appear to have run about terraces on the rock. All this is now gone although large parts of an outer ditch and counterscarp remain.
An outer court to the east, roughly 60m across, is defined by a ditch and counterscarp except on the south, where it rests on headlong crags.

Source: Edwards in Archaeologia Cambrensis XII (1912), 263-94
RCAHM Flintshire Inventory (1912), 20-21
Glen in Archaeologia Cambrensis XV (1915), 47-86, 249-52

John Wiles 27.07.07