Megaliths are ancient manmade structures made of large stones, typically found around the world, dating back to the prehistoric era. They were mostlyused for religious or ceremonial purposes. Synonyms for megalith include dolmen, standing stone, menhir, Henge, cromlech and barrow. Dolmens are typically made up of three or four upright stones supporting a horizontal capstone, while standing stones or monoliths are single large stones that stand alone or in rows. Menhirs are tall, vertically placed stones deeply rooted in the earth. A Henge consists of a circular or oval-shaped enclosure surrounded by a bank and an external ditch. Cromlechs, on the other hand, are a circular arrangement of standing stones in a ditch, and barrows are mounds of earth or stones,used for holding the remains of the dead.