Called by the excavator the 'Rhondda Stonehenge'. Small slabs, set upright, enclose a ring measuring 10.7m NW-SE by 9.1m. The slabs are about 0.6m square and 8-15cm thick; nine survive, but there seem originally to have been fifteen, evenly spaced. Excavation in 1903 showed that the stones wree set upon a wall of laid stones, 1.2 or 1.5m thick. Three 'cist-like structures' with traces of fire were set against the circle, and within it was a rifled cist 1.1m E-W by 0.8m by 0.6m deep, lined with slabs, now probably represented by a hole about 3.7m S of the centre.

A small cairn lies immediately to the NW (Nprn307661); c.20m SE are a second cairn (Nprn307662) and a possible standing stone (Nprn307663).

Site number 368 in: RCAHMW, 1976, An Inventory of the Ancient Monuments in Glamorgan, Volume I: Pre-Norman, Part 1, The Stone and Bronze Ages. Cardiff, HMSO. Page 97.

T. Driver, RCAHMW, 8th September 2008.