The word megalith comes from the combination of two Greek words meaning 'big' and 'stone' and is used to describe constructions which consist of large stones, such as stone circles, stone rows, dolmens and chambered barrows. Megaliths can have a great variation in size. Major megalithic monuments in Europe include Stonehenge and Avebury in England, the chambered mounds of Knowth, Dowth and Newgrange in Ireland, Callanish stone circle and avenues in the Outer Hebrides and the stone rows at Carnac in Brittany.

Society of Leyhunters - finding leys