Dyffryn Ardudwy Burial Chambers are two dolmens, 8.6 metres apart on a bed of white boulders. They are from the Neolithic period. Excavation studies proved that the construction was carried out in two stages. First, a smaller western chamber was created, then a larger, eastern one. They were once covered with a trapezoidal mound of earth and stones (cairn) with an edge encased with smaller stones in order to stabilize the structure. The cairn has been diffused and only a part of the stones scattered around are visible.