<Tr> <Th> Region </Th> <Td> Europe and North America </Td> </Tr> <P> Stonehenge is a prehistoric monument in Wiltshire, England, 2 miles (3 km) west of Amesbury . It consists of a ring of standing stones, with each standing stone around 13 feet (4.0 m) high, 7 feet (2.1 m) wide and weighing around 25 tons . The stones are set within earthworks in the middle of the most dense complex of Neolithic and Bronze Age monuments in England, including several hundred burial mounds . </P> <P> Archaeologists believe it was constructed from 3000 BC to 2000 BC . The surrounding circular earth bank and ditch, which constitute the earliest phase of the monument, have been dated to about 3100 BC . Radiocarbon dating suggests that the first bluestones were raised between 2400 and 2200 BC, although they may have been at the site as early as 3000 BC . </P> <P> One of the most famous landmarks in the UK, Stonehenge is regarded as a British cultural icon . It has been a legally protected Scheduled Ancient Monument since 1882 when legislation to protect historic monuments was first successfully introduced in Britain . The site and its surroundings were added to UNESCO's list of World Heritage Sites in 1986 . Stonehenge is owned by the Crown and managed by English Heritage; the surrounding land is owned by the National Trust . </P>

When were the first stones put up at stonehenge