A dolmen, also known as a portal tomb, portal grave, or quoit, is a type of single-chamber megalithic tomb, usually consisting of three or more upright stones supporting a large flat horizontal capstone. Most date from the early Neolithic period (4000 to 3000 BC). Dolmens were usually covered with earth or smaller stones to form a barrow, though in many cases that covering has weathered away, leaving only the stone "skeleton" of the burial mound intact.
Standing Stones of Stenness Neolithic monument on the mainland of Orkney, Scotland. Just under a mile to the south of the Ring of Brodgar is another smaller neolithic stone monument. With links to Maeshowe (less than a mile to the east) and Skara Brae the sites are all contempory and date to about 3000BCE.