Trail Running > Routes > Brecon Beacons Routes > Craig y Cilau & Mynydd Llangatwg
A diverse 9 km trail run along the limestone escarpment of Craig y Cilau and the wild moorland fringes of Mynydd Llangatwg.
Why run this trail?
Cut into the mountainside high above Llangattock, the limestone cliffs of Craig y Cilau Nature Reserve form a dramatic escarpment of rocks and screes that tumble down from the high moors of Mynydd Llangatwg to the Usk Valley below.
The remains of 18th-century lime workings – tramways and grass-covered spoil heaps – reveal the area’s industrial past, but it has been vigorously reclaimed by nature. The result is a fascinating opening section: compact trails weaving through limestone outcrops and characterful, scrubby woodland, with striking views at every turn.
After skirting Waun Ddu, a raised peat bog (surprisingly dry) the route shifts character. The second half climbs onto the open moorland of Mynydd Llangatwg for a largely pathless fell run along the edge of the escarpment.
A run of two distinct halves, it blends history, variety and cracking views to form one of the Brecon Beacons’ most distinctive outings.
Car Park to Craig y Cilau
Reaching the small car park from the village of Llangattock is an experience in itself – a twisting, single track lane with hairpin bends and gradients that demand low gears while navigating sizeable potholes in the road.
The view from the car park is special – a widescreen backdrop of the Black Mountains above Crickhowell and the Usk Valley. I kitted up quickly to capitalise on a promising break in the clouds and headed onto the main trail through a green metal vehicle gate.
The first section is straightforward – simply follow the line of the escarpment as the path weaves bewteen grassy spoil heaps at its base. It’s fast, easy running on compacted limestone paths and broad grassy trails, with cliffs towering to your left and the wide expanse of the Usk Valley opening out to your right.
Craig y Cilau Nature Reserve to Waun Ddu
The route soon joins an old tramway which curves below the rocks as the wooded slopes of the nature reserve come into view. Scrubby oak and hawthorn trees start to close in before the path suddenly dips away to the right, narrowing into a shaded woodland hollow that feels a little bit magical.
As you climb out of the hollow, the trail becomes rockier and skirts the raised peat bog of Waun Ddu. There’s a broad path that cuts directly across the middle of the bog that actually looks surprisingly dry if you fancy your chances!
Waun Ddu to Mynydd Llangatwg
As the trail curves around the northern tip of the bog it climbs suddenly – passing an information board – and you’ll soon reach a T-junction with a broad vehicle track.
Turn sharp left here onto a faint grassy track through the bracken, climbing steadily towards the furthest visible tip of the escarpment to your right.
As the rocky edge begins to fade into open grassland, turn hard left and continue ascending eastwards towards the clifftops.
Mynydd Llangatwg Escarpment
What begins as a broad, grassy trail soon narrows into a singletrack through the heather as you trace the edge of the escarpment, steadily gaining height.
The path soon disappears entirely across an expanse of rocks and scorched peat – the aftermath of a wildfire in August 2025. It’s a case of picking your own line across some indeterminate, rough sections of very boggy ground. This is more than compensated by a real sense of wilderness and solitude.
Beyond this, the track re-emerges intermittently, winding along the rim of the escarpment. Views open out across to the Sugar Loaf, The Skirrid and the wider sweep of the Black Mountains, with the textured landscape of the nature reserve dropping away below.
A large, sprawling stone cairn marks the approximate halfway point along the escarpment. It’s a natural place to pause and take in the views of the Usk Valley dividing the Black Mountains from the Central Beacons beyond.
Note: This cairn is not the summit of Mynydd Llangatwg (529 m), which lies around 1 km to the south-west across open moorland. It would make a natural extension to this route in summer when the ground conditions are (possibly) less boggy.
Mynydd Llangatwg Escarpment to the car park
From the cairn, follow the network of faint paths to pick up a clearer track descending through a break in the escarpment. The route drops towards an old stone industrial building and the grassy spoil heaps encountered earlier.
Rejoin the main trail and retrace your steps back to the car park to complete a short, punchy and highly varied outing.
For post-run refreshments, nearby Llangattock and the picturesque town of Crickhowell offer good options – though the views from the car park make a strong case for taking your own and lingering a bit longer.
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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.