Wikipedia
Llangattock (or Llangatwg in Welsh) is a village in the Brecon Beacons National Park in Powys , Wales. It lies in the Usk Valley just across the river from the town of Crickhowell. The population of the community at the 2011 census was 999. The Monmouthshire and Brecon Canal passes through the village en route between Brecon and Pontypool.
To the south of the village is the imposing Llangattock Escarpment whose great limestone cliffs were scarred by extensive quarrying in the nineteenth century. Above these is the great gritstone plateau of Mynydd Llangatwg or Llangattock Mountain. Some of Britain's longest cave systems lie concealed beneath this hill, including Ogof y Daren Cilau and Ogof Agen Allwedd together with the shorter though more accessible cave of Eglwys Faen (or 'stone church').
The great natural amphitheatre formed by the cliffs of Craig y Cilau and the quarried Daren Cilau was designated a national nature reserve on account of a variety of rare plants, notably species of whitebeam endemic to the area. The hollow itself is thought to be a product of both glacial action and a massive rotational landslip during the ice ages.