Craig-y-Nos (Welsh for Rock of the Night) is a historic castle and estate located in the upper Swansea Valley, near the village of Pen-y-cae in Powys, South Wales, within the Brecon Beacons National Park (now officially called Bannau Brycheiniog). It is most famous for being the home of the renowned 19th-century opera singer Dame Adelina Patti.