Fan Brycheiniog - Twr y Fan Foel

Fan Brycheiniog and its true summit

Fan Brycheiniog is the highest mountain in the Black Mountain (Y Mynydd Du), in the western part of Bannau Brycheiniog National Park. Twr y Fan Foel is the true summit: a cairn at SN 82437 22065, recorded at 802.5 m by the Database of British and Irish Hills. The prominence is 424 m, and the summit is a Marilyn, Simm, Hewitt and Nuttall.

The familiar trig point and stone shelter belong to a separate, slightly lower top about 290 m away. The knoll beside that trig point is recorded at 801.7 m. Walkers aiming for the main summit should include the cairned top rather than stop at the trig pillar. Fan Foel, farther along the ridge, is another distinct top.

Landscape and geology

Open grassland and moorland meet steep escarpments above the glacial lakes. The rocks are Devonian Old Red Sandstone: Brownstones below the harder Pen y Fan Formation, formerly called the Plateau Beds. These upper rocks formed mainly in rivers, with some shallow-marine environments. Subsequent erosion and glaciation helped shape the cliffs and cwms.

Llyn y Fan Fawr lies below the eastern escarpment. Routes continuing west across Bannau Sir Gaer overlook Llyn y Fan Fach. Clear weather brings views across Fforest Fawr towards Pen y Fan and Corn Du. The Black Mountain here is distinct from the Black Mountains in the eastern part of the national park.

Choosing a route

• Via Llyn y Fan Fawr from Trecastle Road: an east-side circuit crossing the infant Tawe, climbing through Bwlch Giedd, visiting the trig top and Twr y Fan Foel, then descending from Fan Foel to the lower path back towards the lake. The published Wild Trails Wales circuit is 8.2 km, about 3½ hours, with 400 m of ascent.
• From Llyn y Fan Fach car park: a longer two-lake circuit over Waun Lefrith, Picws Du, Fan Foel and the Fan Brycheiniog ridge, returning beneath the escarpments. Carmarthenshire County Council gives 15 km, 5–6 hours and 712 m of ascent. It is a strenuous mountain day.
• From Glyntawe: the short Fan Hir/Fan Foel circuit starts at the Field Study Centre, climbs the Fan Hir ridge and returns past Llyn y Fan Fawr. Saturday Walkers Club gives 15.6 km and 720 m of ascent for this option.
• Direct ascent from near Bwlch Cerrig Duon: use the Trecastle road start at SN853218, cross the Tawe and reach the ridge through Llyn y Fan Fawr and Bwlch Giedd. Return by the same approach if choosing an out-and-back; the Picws Du circuit is a separate extension.
• Beacons Way from Tafarn y Garreg: the ridge section passes Ty Hendry, Allt Fach and Fan Hir before the two Fan Brycheiniog tops. For a summit day, plan the return to Glyntawe. Continuing west to Llanddeusant is a linear journey requiring onward transport or accommodation.

Access and facilities

Choose parking for the approach you intend to walk. Use the designated Llyn y Fan Fach car park near Blaenau, east of Llanddeusant, reached by narrow lanes; leave passing places clear. East-side starts use small roadside parking areas on the Trecastle road. At Glyntawe, follow local parking signs and do not assume pub parking is available without permission.

The T6 bus serves Tafarn-y-Garreg in Glyntawe. Check the current timetable and your return connection. Craig-y-nos Country Park has a café, toilets and pay-and-display parking; it is a separate starting point farther south. Carry food and water for the mountain.

Hazards and care

The escarpments have steep drops and loose ground. Keep back from their edges, particularly in wind, mist, snow or ice. The Bwlch Giedd ascent and Fan Foel descent are steep, and streams and boggy ground can complicate the approach and return. The lower return beneath Picws Du also has narrow, rough sections. Carry a map and compass and know how to use them; choose a route suited to the conditions and the whole group.

Keep dogs close and on a lead near livestock and cliff edges. Twr y Fan Foel and neighbouring Fan Foel contain protected Bronze Age burial monuments. Leave their stones and protective coverings undisturbed.