Dolmen

Dolmen, type of prehistoric chamber consisting of two or more huge unhewn stone slabs, or megaliths, set edgewise in the earth and supporting a flat capstone that serves as a roof. Dolmens were sometimes covered with immense artificial hillocks or tumuli, but at times the covering of earth reached only the capstone. Many dolmens are surrounded by a circle of megaliths collectively called a cromlech. Archaeologists believe that dolmens were burial chambers. They are known to have served as altars, as on the island of Guernsey, where they were used by the Druids in their religious rites. Dolmens are particularly numerous in Ireland and Wales and in the English counties of Devon and Cornwall; in northwest France, especially in Brittany; and in Spain. They are also found in northern Africa, in Syria, and in other countries ranging as far east as Japan. Sometimes the mound enclosing the dolmen was of great size, like that of Sidbury Hill, Wiltshire, England, which was 52 m (170 ft) high and 96 m (316 ft) along the slope.