Stonehenge is a prehistoric monument located in the English county of Wiltshire, about 3.2 kilometres (2.0 mi) west of Amesbury and 13 kilometres (8.1 mi) north of Salisbury. One of the most famous prehistoric sites in the world, Stonehenge is composed of earthworks surrounding a circular setting of large standing stones. Archaeologists had believed that the iconic stone monument was erected around 2500 BC. However one recent theory has suggested that the first stones were not erected until 2400-2200 BC, while another suggests that bluestones may have been erected at the site as early as 3000 BC.