Owned by Forestry Commission. From Parkmill, follow the road to Parc-le-Breos and after half a mile, turn up Green Cwm to Parc-le-Breos megalithic tomb. The cave is 65 metres further up the valley on the right in a crag hidden by trees.
The entrance is 4 metres wide and 6 metres high, It leads to a chamber some 33 metres long with another smaller chamber at the end.
Excavated by E.R.Wood 1860's; 1968; Nash/NMW 2010
The only Palaeolithic engravings (12,500-14,500 years BP) in Wales
SSSI: 0781 Coedydd Parkmill a Cwm Llethrid (Mixed)