2-368-147 - Peter Thompson/Heritage Images

Callanish Stones, Isle of Lewis, Outer Hebrides, Scotland, 2009. The Neolithic stone circle at Callanish (Calanais) dates from approximately 2000 BC. It consists of a ring of 13 stones of Lewisian gneiss, the tallest of which marks the entrance to a burial cairn, although archaeologists believe the cairn was a later addition to the site. Various theories exist concerning the purpose of the circle and the nearby other rows and avenues of stones, including the possibility that they functioned as a form of lunar calendar. A local legend says that the stones are 13 giants who were turned to stone by St Kieran when they refused to convert to Christianity.