History & archaeology
A place made over generations
Cerrig Duon belongs to the Bronze Age ceremonial landscape of the western Brecon Beacons. Later stone clearance may have removed parts of the complex, but enough survives to reveal an unusual combination of ring, solitary monolith and converging alignments.
Twenty stones, none taller than about 0.6 metres, define a circle roughly 18 metres across. Maen Mawr stands immediately beside it. One alignment extends about 42 metres with seventeen small stones; another runs for about 25 metres with twelve stones that can be almost invisible among the grass.
Stories, beliefs & mysteries
Meaning through time
The arrangement may have guided movement or linked ceremonies to the valley and surrounding hills. Modern astronomical and spiritual readings are possibilities rather than demonstrated Bronze Age beliefs. Its name simply means 'black stones', while Maen Mawr means 'great stone'.
No reliable historic ghost tale is known for the monument. The contrast between the dominant Maen Mawr and near-hidden rows often gives visitors a sense of discovery, but that emotional response should not be turned into invented folklore.
Plan a visit
Walk gently into the landscape
Reach the area from the old Trecastle road off the A4067 and navigate by the grid reference. The river crossing from the informal parking area can be hazardous and must not be attempted after heavy rain; visit with a companion, carry a detailed map and turn back if conditions are doubtful.
Do not climb, move stones, light fires or leave offerings. Follow current access signs and take everything home.
Sources & further reading
Follow the evidence
Coflein / Royal Commission on the Ancient and Historical Monuments of WalesCerrig Duon stone circle↗This introductory record was last reviewed in August 2026. Access details can change; consult the site manager before travelling.
The marker shows the monument, not a parking space. A postcode is only a navigation aid; check current access and parking information before travelling.