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Circles of Stone field guide

Cerrig Duon

Powys, Wales

Before you go

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.

Grid reference
SN 851 206
Monument coordinates
51.87230, -3.66980

Pack and plan

  • Charged phone and a paper map or saved offline map
  • Water, layers and footwear suited to the terrain
  • Current weather, daylight and access information checked
  • Someone told where you are going on remote walks

Open monument map ↗

What you are looking for

A low circle, the great Maen Mawr monolith and two delicate stone rows form one ritual complex above the River Tawe.

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.

Field notes

Weather and light: ______________________________________________

First feature spotted: ___________________________________________

Something the map did not show: _________________________________

Walk gently

  • Check current access and weather before setting out.
  • Keep dogs under close control around livestock.
  • Do not climb, move stones, light fires or leave offerings.
  • Take all litter home and protect fragile ground.

If something goes wrong

In an emergency call 999 or 112. Give the grid reference or coordinates above, describe your approach route, and do not put yourself at further risk.

Guide reviewed August 2026 · circlesofstone.co.uk/circles/cerrig-duon

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