Tŷ Mawr Hut Circles are situated at the base of Holyhead Mountain close to South Stack. There are the remains of a Celtic Iron Age settlement comprising of circular huts and rectangular buildings. There is also another group of round stone huts close by and there is some evidence that the site was occupied in the Middle Stone Age, Neolithic, Bronze and Iron Ages. The site is located west of Holyhead, Holy Island, Anglesey, Holy Island, Anglesey, Wales (Welsh: Caergybi,Ynys Gybi, Ynys Môn, Cymru) close to South Stack.