Immediately south of the town of Builth Wells, between the two north-south roads the A470 and the B4520 'Eppynt' road to Brecon, opens out an expanse of moorland, on which you'll find, at the foot of Banc y Celyn (472m), the 8 acre Pant y Llyn lake. Small concrete dams retain the water to the north and west ends of the lake, which is managed as a coarse fishery by the Wye and Usk Foundation.