Glyndyfrdwy Castle, better known as Owain Glyndwr`s Mount is situated adjacent to the main A5 trunk road 2 miles East of Corwen. Built in the 12th Century, this was the seat of the Lords of Glyndyfrdwy, of whom Owain Glyndwr was the 6th to bear that title. According to Iolo Goch, his bard, a wooden castellet stood upon a great mound. It is claimed that it was on this site on 16th September 1400 that Glyndwr raised his standard for the first time to proclaim himself Prince of Wales.
The mound itself stands 6.5m high, 36m across at the base, and 12m across at the top, with a ditch 1m deep on the West and South West. As at other similar sites in the area (eg Rug, Prysor), there is no trace of a bailey, however, in the case of this site there is a nearby moated area which was destroyed in 1403.