Bedd Arthur consists of a barely visible oval bank and ditch, with thirteen standing stones, none higher than 0.6m arranged inside along with two further fallen stones. The stone layout measures around 20m by 10m. The shape is not well defined and is generally described as sub-rectangular but has been described as a rectangle, a horseshoe, an oval and a pointed ellipse. Such arrangements of stones are also found at a site known as the 'Churchyard' on Skomer Island, and were adopted at Stonehenge itself and Bedd Arthur has been suggested as a prototype.
The stones appear to be leaning inwards, suggesting that they were originally placed on the flanks of a mound which has since disappeared. There is also one "truncated end", similar to the portal on some elongated Neolithic burial mounds. There may have been a burial chamber in the middle of the stone setting: it would not be exceptional for the mound itself to have been removed by erosion or grave hunters, which is what has happened to the Bedd yr Afanc passage grave on the northern side of Mynydd Preseli.
It is one of many sites in the British Isles to be claimed by local folklore as the burial place of King Arthur. The site has not been excavated and is absent from authoritative surveys. Its authenticity and relationship to Stonehenge are therefore unconfirmed.