This walk follows a course along the western slopes of Fan Llia to the head of the Llia valley, across Bryn Melyn and Cefn Perfedd into Cwm Dringarth and tributary stream valleys below Fan Dringarth, and down Cwm Dringarth above the Ystradfellte Reservoir, returning to the carpark across the southern extent of Cefn Perfedd. The walk is notable for monuments of prehistoric, medieval and post-medieval date which can be seen along its route. This is a quiet area for walking being well hidden from more popular routes.
The starting point is the parking and picnic area at SN92721646 on the unclassified road between Ystradfellte and Heol Senni which can be accessed on the south via the A4125 from Sennybridge and Defynnog.