The Brecon Beacons National Park was established in 1957, the third of the three Welsh parks after Snowdonia in 1951 and the Pembrokeshire Coast in 1952. It stretches from Llandeilo in the west to Hay-on-Wye in the northeast and Pontypool in the southeast, covering 519 square miles and encompassing four main regions – the Black Mountain in the west, reaching 802 metres at Fan Brycheiniog, Fforest Fawr and the Brecon Beacons in the centre, including the highest summit in the park and in South Wales at Pen y Fan 886 metres and the confusingly named Black Mountains in the east, where the highest point is Waun Fach 811 metres.
The Black Mountains in the east are clearly separated from the central Beacons by the Usk valley between Brecon and Abergavenny. The other three regions form a continuous massif of high ground above 300m, and the divisions are less clear; the A470 road forms the approximate boundary between the central Beacons and Fforest Fawr, while a minor road from Sennybridge to Ystradgynlais divides Fforest Fawr from the Black Mountain range to the west.
The entire national park achieved the status of being an International Dark Sky Reserve in February 2013.