Black Mountain Pass

The Black Mountain Pass is the stretch of the A4069 that crosses the Black Mountain (Y Mynydd Du) between Llangadog in the north and Brynamman in the south. It runs over the western edge of Bannau Brycheiniog (Brecon Beacons) National Park in Carmarthenshire, Wales, for about 20 miles.

The road has appeared on Top Gear, and its best known corner is Tro Gwcw, Cuckoo's Bend, a tight hairpin on the climb.

The road over the mountain dates from 1819. Limestone was once quarried near the top, and the old workings of Herbert's Quarry still sit beside the road.

• From Llangadog the A4069 climbs out of the valley onto open moorland, through the Tro Gwcw hairpin.
• Near the top, the Quarry car park sits beside the old Herbert's Quarry limestone workings. A walking route leaves from there up Garreg Lwyd and on towards the lake of Llyn y Fan Fach.
• Sheep graze the open mountain and often stand on the road itself.
• From the top the road drops south off the mountain to Brynamman.
• Best way to experience it: driving or riding it yourself, in your own vehicle or a hire car.

• A 40 mph limit applies between Brynamman and Llangadog, enforced by average speed cameras run by GoSafe and Carmarthenshire Council. The limit was cut from 60 mph after serious and fatal crashes.
• The Quarry car park near the top is the named stopping place on the pass. Carmarthenshire Council runs a road weather camera there with live air and road surface temperatures.
• Llangadog sits at the north end of the pass and Brynamman at the south end.

Last verified: 3 November 2026
Official link: https://www.carmarthenshire.gov.wales/council-services/highways-travel-parking/road-weather-cameras/a4069-black-mountain-quarry-car-park/