Cwmtwrch is a village in the Swansea Valley, southern Wales, some 15 miles north of Swansea.
The name Cwmtwrch (Valley of the Wild Boar) derives from the “twrch trwyth” (mythical wild boar) of King Arthur’s legends and the ancient tales of the Mabinogion in early Welsh literature. The legend relates to one of Arthur’s tasks: to rid the western Brecon beacons of the pack of wild boars that were terrorizing the people. Arthur chased the boars from Dyfed eastward towards Powys. On the Black Mountain, he picked up a large stone (carreg fryn fras) and cast it towards the wild animals, striking dead the leader of the pack on the edge of a the valley near Craig-Y-Fran Gorge. The big boar's body rolled down the valley and into the river which is now the River Twrch. The big stone is still on the mountain. In this area also is the legend of the lady of the lake of Llyn-y-fan.
Cwmtwrch has been split into two parts, Upper Cwmtwrch (Cwm Twrch Uchaf) and Lower Cwmtwrch (Cwm Twrch Isaf), due to the traversing of the now defunct railway line and road at two points requiring an upper and lower gate. The Upper and Lower tag is something that has made Cwmtwrch a joke in Wales considering its small size.
The village lies in three counties Powys, Carmarthenshire and Neath Port Talbot. The Lowthers Restaurant (formerly the George IV Inn Public House) is built where the three counties meet, and this made it interesting in the past, due to different licensing hours between counties
Nearby villages are Ystradowen, Rhiwfawr, Ystradgynlais, and Ystalyfera.
Cwmtwrch has a school, a public hall, and a few chapels, pubs, and shops. A notable feature of Cwmtwrch is the ffynon which is a natural spring appearing at a memorial. The water is highly sulphuric and smells of rotten eggs, but it is claimed by the locals that it has healing properties, and people from as far away as Argentina have been there to collect water for drinking.
The village's most famous resident is Clive Rowlands, former Wales national rugby union team captain, who also managed both the national team and the British Lions.