The roof of this inner chamber is supported on several upright stones acting as pillars. The roof of the passage and the chamber is built from large, flat slabs of stone.
First discovered in 1827, the site was excavated by a pair of enthusiastic antiquarians in 1857, and is said to have been empty, however, the area above ground level contained domestic refuse, and several ancient walls, but there are no traces of this now. A recent investigation revealed the presence of a second earth house about 20 feet away, with traces of an Iron Age building above it, suggesting that there was a settlement at Grain and the two sites are related.
The site is rather lost in the middle of an industrial estate, and isn't immediately obvious - look for a low green mound near the road junction.