View of the Pistyll Rhaeadr Waterfall. The waterfall is located in Llanrhaeadr ym Mochant in the Tenamt valley. It is over 240 feet high, is the highest waterfall in England and Wales and has its source in the Berwyn Mountains. It was one of the 7 Wonders of Wales. There are many legends surrounding the waterfall and one suggests that its name originated from the Roman occupation of Britain- during this time statues of Rhae, the mother of Zeus were carried by soldiers as symbols of luck and there was a settlement and fort near the location of the waterfall.