This site is described in the National Monument Record (accessible via Coflein and Historic Wales as a megalithic structure/summer house and is classified "Early Medieval?". The following text is given as the site description:
A peculiar 'megalithic' structure set on a low hillock overlooking and to the W of Dolbadarn Castle.
It is primarily defined by two large orthostatic slabs set parallel to each other some 3m apart forming two sides of a square structure which has low pillars at each corner. Contiguous with the NE corner pillar is a larger 2m high squarish 'standing stone'. Numerous other blocks lie scattered about and the whole area is raised some 0.5m above the surrounding hillside.
The eight figure grid reference for the site is SH58455977, and the National Primary Record Number (NPRN) is 300841.