The finest feature (and the highest point) of the Black Mountain is the sweeping escarpment of Fan Brycheiniog (802m), reached via a fairly strenuous 11.5-mile loop from Glyntawe on the A4067.
The initial precipitous ascent of the Fan Hir ridge eases into a spectacular ridge walk, with views of the Llyn y Fan Fawr glacial lake to the east. A steep path climbs up to Fan Brycheiniog and it's worth detouring to climb Fan Foel for the views of Llyn y Fan Fach before following the almost level Bannau Sir Gaer ridge to the Waun Lefrith summit. Head west across pathless terrain to the rocky Carreg yr Ogof, and descend the path to the east of it across a wild landscape of limestone sinkholes, marshland and streams.