Trail Running > Routes > Brecon Beacons Routes > Blaen Llia (Fforest Fawr)
A 22 km trail run through the remote uplands of the Brecon Beacons and the quiet peaks of Fan Nedd and Fan Gyhirych.
–Route Link-Up– This route forms part of the Fforest Fawr Round – a 38 km mountain run offering one of the most comprehensive tours of the Fforest Fawr uplands in a single, continuous circuit. View Route
Why run this trail?
This run feels as remote as you’re likely to find in the Brecon Beacons. It’s a 20 minute drive from the nearest A-road on winding single track lanes to reach the car park at Blaen Llia. The effort is rewarded with deserted trails and a sense of wilderness that you won’t find on the main tourist drags.
The plateau of rough moorland here forms part of the ancient Great Forest – a royal hunting ground dating back to the 12th century. It also bears the marks of more recent industry, with shake holes, disused quarries and mine shafts peppering the landscape. If that’s not enough history, the run is bookended by short sections of Sarn Helen – a 2,000 year old Roman road that once spanned the entire length of Wales.
This route is an excellent fell running circuit in an area of the national park that makes you realise how elusive true solitude has become. You’re likely to have big sections of these wild, beautiful trails to yourself whatever the weather.
Sarn Helen to Fan Nedd
The route sets out north from the car park at Blaen Llia. After a couple of kilometres of easy running on the lane, an inconspicuous stile on the left directs you onto the moor to start the climb.
This is the most direct route up Fan Nedd (663 m) and definitely the least used – the faint track soon fragments into boggy ground. I picked the highest lines and sheep trods in an effort to stay dry for as long as possible.
It’s a succinct kilometre of running to reach the summit and the final push to the top is brutally steep. I stole a couple of tactical pauses to admire the valley below as it grew distant.
The summit of Fan Nedd affords great views – east towards the central mountains of Pen y Fan and Corn Du and west to Fan Gyhirych – today’s second summit – with the Black Mountain providing a dramatic backdrop.
A short hop from the trig point brings you to a cairn at the north end of the peak. This switches the aspect nicely and provides a viewpoint of the rolling Senni Valley below.
Fan Nedd to Fan Gyhirych via Bwlch y Duwynt
Getting across to Fan Gyhirych involves an exciting descent from Fan Nedd. It’s steep and eroded in places and requires constant focus. After I had slogged up Fan Nedd, it felt good to push the pace and enjoy the pull of gravity, the picturesque valley stretching out below. At the bottom of the descent, the path rises again to join a rough gravel track at Bwlch y Duwynt.
From here the long ridge and curling lip of Fan Gyhirych come properly into view. There’s a brief, unwelcome section of gravel lane to join the grassy trail to the top.
The rather forlorn trig point on the summit of Fan Gyhirych (725 m) is incidental. The real prizes here are the stunning views – west across to Fan Hir and Fan Brycheiniog and south towards Cribarth and Carreg Goch, with the Swansea Valley fading to the coast. Warmed by the sun and the vistas, I sat in the grass among the sheep, grinning contentedly to myself. The benefits of quiet trails!
Shake Holes, Railways and a Roman Road
From Fan Gyhirych, it’s mostly downhill. A short descent drops you back onto the gravel lane for a couple of knobbly kilometres before veering off once more onto softer moorland and a section of the dismantled Neath and Brecon Railway. The faint lines of wooden sleepers still poke through the turf – a quirky aid for stride-watchers.
The landscape here is dotted with reminders of the area’s industrial past. Shake holes, disused quarries, and the occasional covered mine shaft add a pleasing contrast to the run.
The route eventually joins the Beacons Way, winding across open moorland between distant pine plantations. There’s a couple of lumpy climbs to tick off in the final stretch before the ancient Roman road of Sarn Helen marches you back to the starting point at Blaen Llia in full Legionary glory.
As I sat by the clear flowing water of the river and reflected on my run, I scrabbled around for a suitable coda to this post. “Veni, Vidi, Vici”… could I really get away with that?
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Disclaimer
All routes and GPX files are provided as a guide only. Conditions, rights of way, and landmarks may change. Always carry an up‑to‑date map and use your own judgement. See the Trail Run Disclaimer page for details.