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
Tal y Fan Tal y Fan Tal y Fan is an outlying peak of the Carneddau mountains in North Wales. It is one of the four Marilyns that make up the Carneddau, the others being Carnedd Llywelyn, Pen Llithrig y Wrach and Creigiau Gleision. It is high, and lies midway between the Conwy valley to the east and Penmaenmawr on the coast to the north-west. It is the most northerly 2000 ft summit in Wales. On 6 May 2013 BBC News reported that a precise GPS measurement of Tal y Fan's height had been verified by the Ordnance Survey as 609.98 metres or