Ty-Newydd is a ruined megalithic chamber which has a massive cracked capstone, about 4.0m by 1.8m and up to 1.2m thick, that rests on three of the four remaining uprights. The chamber was excavated in 1936 when it was found to be about 2.8m by 1.2m, its area defined by a spread of charcoal with a hearth at the eastern end, where there is thought to have been a second chamber or passage. Finds included Beaker pottery of the Bronze Age and this may represent the reuse of an earlier, Neolithic monument. The chamber iss set up on a natural outcrop and would originally have been embedded in a mound or cairn. It is said to have once been enclosed by a circular wall about 32m in diameter and this may reflect the form of the cairn.
Sources: Phillips in Archaeologia Cambrensis 91 (1936), 93-99
RCAHM Anglesey Inventory (1937), 65
Lynch 'Prehistoric Anglesey' (1970), 28-9
J.Wiles, RCAHMW, 19 March 2003.