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 Boncyn Trefeilw Y Groes Fagl. Pen y Boncyn Trefeilw Pen y Boncyn Trefeilw is a subsidiary summit of Cyrniau Nod in north east Wales. It forms a part of the Berwyn range called the Hirnantau. It has two tops: Stac Rhos and Pen y Cerrig Duon. Pen y Cerrig Duon is now listed as a deleted Nuttall due to re-surveying. The views from the summit are extensive, if unremarkable due to the featureless, flat moorland surroundings. The summit is marked by a small cairn, is which located only a few metres from a track road that continues on to the pass between