A dolmen is a type of single-chamber megalithic tomb, usually consisting of two or more vertical megaliths supporting a large flat horizontal capstone. Most date from the early Neolithic (4000-3000 BC) and were sometimes covered with earth or smaller stones to form a tumulus. The oldest known are found in Western Europe, dating from 7,000 years ago. They are regarded as tombs or burial chambers, despite the absence of clear evidence for this. Colorized version of an illustration from Primitive Man by Louis Figuier, 1870.