Stonehenge

A megalithic monument put up in several phases between 3000 and 2000 BC on Salisbury Plain, England. Its great outer circle had thirty upright sandstone blocks linked by lintels; inside stand five enormous trilithons in a horseshoe and several groups of bluestones brought from Wales. What it was for is still debated: ceremonial ground, solar observatory, burial site, or several of those at once.