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Mountain walking; steep summit approaches

Corn Du

872m Elevation
28m Prominence
Wales Country
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Overview

Corn Du (871.5 m) is the flat-topped neighbour of Pen y Fan in the central Bannau Brycheiniog (Brecon Beacons), Powys. Its reconstructed Bronze Age cairn stands above the steep-sided Cwm Llwch. Routes approach from Pont ar Daf, Storey Arms, Cwm Gwdi and the Neuadd valley.

Corn Du

Corn Du rises to 871.5 m beside Pen y Fan in Powys, in the central Bannau Brycheiniog (Brecon Beacons). The flat summit overlooks the steep-sided Cwm Llwch and its small lake. Its prominence is 28.2 m; the Database of British and Irish Hills records it as a Nuttall and sub-Simm.

Summit and geology

A large reconstructed Bronze Age burial cairn marks the summit. Respect this archaeological feature and leave its stones in place. The National Trust's heritage record describes excavations in 1978 and 1992.

The mountain is built from Devonian sedimentary rocks of the Old Red Sandstone. The relatively resistant Pen y Fan Formation, formerly called the Plateau Beds, caps the Brownstones Formation and contributes to the flat top. Ice helped shape the steep northern cwms. This is not a volcanic summit.

Choosing an approach

Pont ar Daf and Storey Arms are separate starting places on the A470. The direct Pont ar Daf approach crosses the footbridge and climbs to Bwlch Duwynt. From there, choose the Corn Du summit path; a path around its southern slope bypasses the summit towards Pen y Fan. A Corn Du-only out-and-back returns to Pont ar Daf by the same approach.

For a circuit over both summits, the route card describes Walking Britain's Pont ar Daf start via Storey Arms, returning by Bwlch Duwynt. Its complete route is 7.5 km, with 515 m ascent and a published estimate of 3 hours 50 minutes.

The northern circuit starts at Cwm Gwdi, climbs Cefn Cwm Llwch to Pen y Fan, crosses Corn Du, and returns through Cwm Llwch and the lanes. Walking Britain gives 12.2 km, 667 m ascent and 5 hours 40 minutes. Pen y Fan is part of this circuit, rather than an optional extension.

The longer ridge approach from Taf Fechan car park reaches Lower Neuadd, climbs Graig Fan Ddu and continues north to Corn Du. The out-and-back described here retraces that line. Do not use the distance or time of the full horseshoe over Pen y Fan and Cribyn for this different itinerary.

Fan Fawr is on the other side of the A470 valley. There is no direct summit ridge joining it to Corn Du.

Access and preparation

Use designated parking and check current National Trust charges and local notices. Public toilets are at Pont ar Daf; bring your own drinking water. Buses stop at Storey Arms, but check both outward and return services before travel. Keep dogs on short leads around livestock and follow local signs.

These are mountain walks with steep, uneven paths and exposed escarpment edges. Carry a detailed map, compass, waterproofs, warm layers and a torch. Clouds can hide the correct descent at Bwlch Duwynt. Keep away from the northern drops; snow and ice make steep paths more serious. In an emergency call 999 and ask for Police, then Mountain Rescue.

Nearby and heritage

Pen y Fan (886 m) is the closest higher summit; Cribyn is 793.8 m. The Tommy Jones memorial obelisk lies northwest of Corn Du and commemorates the child who became lost here in 1900. The Fforest Fawr Geopark offers “black stack” or “black horn” as possible meanings of Corn Du, rather than a single certain translation.

Explore routes near Corn Du

Walks starting near this hill. Open a route to check its map, distance and full itinerary.

Pen y Fan via Corn Du from Storey Arms

7.2 km ~3h Moderate

View route

Brecon Basin to Brynich Aqueduct: Canal Towpath Walk

7.3 km ~2h 15m Easy

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A Very Merry Winter Walk ending with Cake & a Hot Drink!

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Merthyr Tydfil with Men Walking & Talking

View route

Route planning notes

These notes describe possible approaches. Check a route's map and access information when planning your walk.

Corn Du and Pen y Fan via Storey Arms (Pont ar Daf circuit)

Circular from Pont ar Daf (SN987200). Walk north beside the A470 to Storey Arms, climb past Y Gyrn and cross Blaen Taf Fawr to Corn Du, then Pen y Fan. Return to the saddle, take Corn Du's southern bypass to Bwlch Duwynt, and descend the main path to Pont ar Daf. Walking Britain gives 7.5 km, 515 m ascent and 3 hours 50 minutes. Take care at the stream and summit steps.

7.5 km Moderate mountain walk

Corn Du from Pont ar Daf (out and back)

From Pont ar Daf (SN988199), cross the footbridge and climb to Bwlch Duwynt, then take the summit path to Corn Du. Return down the same approach to the same car park. Pen y Fan is an optional extension over the connecting saddle, with the extra climb and return added to the day. Keep clear of the steep northern edge; the broad approach becomes steeper and stonier near the summit.

Moderate mountain walk

Pen y Fan and Corn Du: Cwm Gwdi/Cwm Llwch circuit

From Cwm Gwdi (SO024248), climb Cefn Cwm Llwch to Pen y Fan and cross to Corn Du. Descend southwest to SO005209, turn north to the Cwm Llwch rim, then follow the obelisk and lake-valley path to Cwm-llwch. Follow lanes via SO011252, SO020252 and SO025251 back to Cwm Gwdi. Walking Britain gives 12.2 km, 667 m ascent and 5 hours 40 minutes. Watch traffic on the return lanes.

12.2 km Strenuous mountain circuit

Corn Du via Neuadd and Graig Fan Ddu (out and back)

Start at Taf Fechan car park (SO038169), south of Lower Neuadd. Follow the road north to the old pump house, climb west onto Graig Fan Ddu, and follow the ridge north via Bwlch Duwynt to Corn Du. Retrace that ridge, the steep reservoir-side descent and the road to the same car park. This uses the outward part of the National Trust horseshoe, with a return along the same exposed ridge.

Strenuous mountain walk
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Hill facts and local notes

Classifications

Nuttall High Hills of Britain Subsimm

Elevation

872m

2,859 ft

Prominence

28m

Coordinates

51.8817, -3.4438

SO007213

OS Map

160

Explorer: OL12E

At the Summit

A large reconstructed Bronze Age burial cairn crowns the flat summit beside the steep northern escarpment. Leave the cairn stones undisturbed.

Terrain & Geology

Stone-pitched and gravel mountain paths rocky summit steps grassy ridges and wet or boggy ground away from the main paths. The northern escarpment has steep drops.

Corn Du is formed from Devonian sedimentary rocks of the Old Red Sandstone. Sandstones and siltstones of the Brownstones Formation underlie the harder Pen y Fan Formation, formerly called the Plateau Beds, which helps form the flat summit. Glaciers modified the northern cwms and steep escarpments.

Views & Scenery

In clear weather, the summit overlooks Cwm Llwch and Llyn Cwm Llwch, with Pen y Fan close to the northeast. Wider views include the Usk valley and Brecon to the north and the western Beacons.

History & Heritage

Name Origin

The Fforest Fawr Geopark gives possible meanings of "black stack" or "black horn" for Corn Du. The precise interpretation is uncertain.

Historical Significance

The summit cairn is a reconstruction of a Bronze Age burial monument. National Trust Heritage Records records excavation of the central cist in 1978 and more extensive work in 1992 after erosion. The Tommy Jones obelisk northwest of the summit commemorates a child who became lost on the mountains in 1900.

Getting There & Facilities

Parking

Pont ar Daf (SN988199), beside the A470 near Storey Arms, is the main National Trust car park. Cwm Gwdi (SO024248) serves the northern circuit; Taf Fechan (SO038169) serves the Neuadd approach. Storey Arms is a separate start with limited parking. Use designated spaces and check current charges and notices; do not park on the A470 or block access.

Public Transport

Buses serve Storey Arms on the A470, with links from Brecon and Merthyr Tydfil. Check the current Traveline Cymru or operator timetable and your return bus before setting out; allow time to reach the stop from your chosen route.

Nearby Facilities

Public toilets are at Pont ar Daf. Do not rely on visitor facilities inside the Storey Arms education centre. Bring food and all the water you need; the National Trust says there is no drinking-water refill at Pont ar Daf.

Safety Information

Known Hazards

  • Steep drops border the northern summit and Cwm Llwch rim. Keep to the paths and well back from the edge, especially in wind or cloud.
  • The Corn Du summit approaches include steep rocky or pitched steps. Wet or icy surfaces can be slippery.
  • Mist can conceal descent junctions at Bwlch Duwynt. Check the return direction with a detailed map and compass; a popular path is not a substitute for navigation.
  • The Storey Arms circuit crosses Blaen Taf Fawr; assess the stream in wet conditions. The Cwm Gwdi circuit also has narrow lanes with traffic.

Seasonal Hazards

Snow and ice can make the steep summit paths and the descent to Pont ar Daf hazardous. Match winter plans to your skills and equipment, and allow for short daylight. Cold, wind and rain can affect the tops even when the car park feels mild; carry a torch, warm layers and waterproofs.

General Safety Tips

  • Check weather conditions before setting out
  • Carry appropriate clothing and equipment
  • Let someone know your planned route
  • Take a map, compass, and GPS device
  • Carry emergency supplies: food, water, first aid kit, torch

Hills

Some common questions about the hills answered

Are there group walks up Corn Du?

Many walkers use Walkmates to join or organise walks with others. You can check for group walks around Corn Du through the maps

Are there other walkers around Corn Du?

Activity varies by location and time, but Walkmates lets you see whether others have shared walks or shown interest in this area. Find other people through the walking friends search walking friends for Corn Du search or of course create your own walk for Corn Du

Can I organise a walk to Corn Du?

Yes. If there aren’t any walks listed already, you can create a walk and make it available for others to join.

If you're signed up to Walkmates, you can create a walk to Corn Du.

How do I find a walk up this hill?

There are often multiple ways to walk this hill, depending on experience and route preference. Walkmates helps you explore walks and routes that others have shared.

Can I suggest a new route up Corn Du?

Yes. You can suggest or create routes to share with others. Walkmates focuses on the social side of walking, so routes are used to help people organise walks and explore areas together, rather than as detailed navigation tools or route libraries.

Other uses really appreciate knowledgeable walkers sharing their routes. Share your favourite route to Corn Du here

The is an error or something incorrect about this hill. How do I let you know?

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Location

Corn Du location map

Grid reference: SO007213

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