Llyn y Fan Fach of the Lady of the lake in Welsh and English. Llyn y Fan Fach Llyn y Fan Fach (Welsh meaning "Lake of the small hill") is a lake of approximately 10 hectares on the northern margin of the Black Mountain in Carmarthenshire, South Wales and lying within the Brecon Beacons National Park. The lake lies at an altitude of approximately , immediately to the north of the ridge of the Carmarthen Fans. It is the smaller of two lakes within this mountain massif: the slightly larger Llyn y Fan Fawr is about to the east. The lake is overlooked by
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