The village of Porth y Nant, now Nant Gwrtheyrn, was built for quarry workers in the 19th century, when granite was dug out of the surrounding mountains and shipped to Liverpool, Manchester and elsewhere to be used in building roads. The quarries closed after WWII and the village was gradually abandoned. After being used for the New Atlantic Commune in the 1970s, it was given a new lease of life when the Welsh Language & Heritage Centre opened in the restored buildings, in 1982, offering residential Welsh-language courses.
Nant Gwrtheyrn has an isolated and dramatic setting, reached by a preposterously steep road down into the valley, accessed from the village of Llithfaen (on the B4417). If you're driving, take it very slowly and be extremely careful. Otherwise it's a 25-minute walk from the car park at the top of the hill.