The structure is located on the scarp edge of a south-facing slope, on the edge of a track terraced into the hillside. This track appears to be the outer edge of a landscaped terrace upon which Pen yr Alltwen farm buildings were built.
From the track the site presents in much the way described by Cadw. One large slab surrounded by leaning and fallen smaller slabs and blocks, supposedly a collapsed chamber, and a second adjacent slab with similarly disposed blocks suggesting a second, smaller, chamber to the immediate NW.
When seen from below, that is downslope from the track, the structure appears to be eroded outcrop. The larger slab seems to be a block dislodged from the exposure along a bedding plane. If the track is followed a short distance to the S it is seen to be formed on levelled outcrop. It is therefore hard to avoid the conclusion that this site is no more than a fortuitous arrangement of stones created by surface levelling. But by the same token a former built structure may have been shifted by the same process resulting in the disturbed remains visible today. There are no traces of a cairn, and if the site is genuine the location would have afforded little prospect of one, unless the subsequent landscaping was so radical as to have altered completely the configuration of the local ground pattern.
visited DKL 3 November 1999
The site was visited ten years earlier on the basis of an antiquarian sighting of a possible cairn.
No trace of cairn or enclosure (formed by orthostats) was found at any point on the 'foot of the slope' to the immediate S of Pen yr Alltwen. Neither the farmer at Alltwen Ganol nor the present tenant of the land once belonging to Pen yr Alltwen knew of any former discoveries on this land.
visited DKL 7.9.1989
visited D.K.Leighton 3 November 1999