One of the impressive circular stone huts known as Cytiau'r Gwyddelod - 'The Irishmen's Huts' at Ty Mawr, near South Stack, Anglesey. First excavated in the 1860's when at least fifty buildings were recorded. Many of the huts were partly restored in the early 20th century and areas were re-excavated between 1978-82. Today only twenty buildings remain. There is evidence for occupation from the Mesolithic through to Early Medieval periods with finds ranging from flint arrowheads, stone tools, pottery and Roman coins. The main standing remains are probably from the Iron Age. The round houses would have had low stone walls on which roof timbers would have rested with a thatch or turf roof.