Pen y Fan Pen y Fan Pen y Fan () is the highest peak in south Wales, situated in the Brecon Beacons National Park. At above sea-level, it is also the highest British peak south of Cadair Idris in Snowdonia. The twin summits of Pen y Fan and Corn Du at 873 m (2,864 ft) were formerly referred to as Cadair Arthur or 'Arthur's Seat'. The mountain and surrounding area are owned by the National Trust whose work parties attempt to combat the erosion caused by the passage of thousands of feet up and down this most popular of South Wales' peaks. The
Pen y Clawdd Castle a medieval fortified site rather than a castle. Pen y Clawdd Castle Pen y Clawdd Castle is a ditched mound with a double moat, roughly circular in shape, with a diameter of approximately 28m to 30m and about 2.4m high. The castle is in Llanvihangel Crucorney, about five miles to the north of Abergavenny, Monmouthshire, in south east Wales and lies between the Usk and Monnow rivers. The mound was designated a scheduled monument in 1950 and described as a defensive medieval motte. The castle mound is adjacent to Pen-y-Clawdd Court (a Grade I listed building), a stable and cowshed