Stonehenge is a prehistoric monument located in the English county of Wiltshire, about 8 miles (13 km) 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. Archeologists believe the standing stones were erected around 2200BC and the surrounding circular earth bank and ditch, which constitute the earliest phase of the monument, have been dated to about 3100BC. The site and its surroundings were added to theUNESCO´s list of World Heritage Sites in 1986 in a co-listing with Avebury henge monument, and it is also a legally protected Scheduled Ancient Monument. Stonehenge itself is owned by the State and managed by English Heritage while the surrounding land is owned by the National Trust.

Many aspects of Stonehenge are subject to debate. What was its function: an astronomical observatory, a religious site, or something supernatural? Who built it, and how?

Stonehenge is also mentioned within Arthurian Legend. Geoffrey of Monmouth said that Merlin the wizard directed its removal from Ireland, where it had been constructed on Mount Killaraus by Giants, who brought the stones from Africa. After it had been rebuilt near Amesbury, Geoffrey further narrates how first Ambrosius Aurelianus, then Uther Pendragon, and finally Constantine III, were buried inside the ring of stones. In many places in his Historia Regum Britanniae Goffrey mixes British legend and his own imagination; it is intriguing that he connects Ambrosius Aurelianus with this prehistoric monument, seeing how there is place-name evidence to connect Ambrosius with nearby Amesbury.

According to Geoffrey of Monmouth, the rocks of Stonehenge were healing rocks which Giants brought from Africa to Ireland for their healing properties. These rocks were called The Giant's Dance. Aurelius Ambrosias (5th Century), wishing to erect a memorial to the nobles (3000) who had died in battle with the Saxons and were buried at Salisbury, chose (at Merlin's advice) Stonehenge to be their monument. So the King sent Merlin, Uther Pendragon (Arthur's father), and 15,000 knights to Ireland to retrieve the rocks. They slew 7,000 Irish. As the knights tried to move the rocks with ropes and force, they failed. Then Merlin, using "gear" and skill, easily dismantled the stones and sent them over to Britain, where Stonehenge was dedicated. Shortly after, Aurelius died and was buried within the Stonehenge monument, or "The Giants' Ring of Stonehenge".

By the beginning of the 20th century a number of the stones had fallen or were leaning precariously, probably due to the increase in curious visitors clambering on them during the nineteenth century. Three phases of conservation work were undertaken which righted some unstable or fallen stones and carefully replaced them in their original positions using information from antiquarian drawings.

In 1915 Cecil Chubb bought Stonehenge, through Knight Frank & Rutley estate agents, for £6,000 as a present for his wife. She gave it to the nation three years later. The item was listed in the catalogue as "Lot 15. Stonehenge with about 30 acres, 2 rods, 37 perches of adjoining downland."

Stonehenge is a place of pilgrimage for neo-druids and those following pagan or neo-pagan beliefs. The midsummer sunrise began attracting modern visitors in the 1870s, with the first record of recreated Druidic practices dating to 1905 when the Ancient Order of Druids enacted a ceremony. Despite efforts by archaeologists and historians to stress the differences between the Iron Age Druidic religion and the much older monument, Stonehenge has become increasingly, almost inextricably, associated with British Druidism, Neo Paganism and New Age philosophy. After the Battle of the Beanfield in 1985 this use of the site was stopped for several years, and currently ritual use of Stonehenge is carefully controlled.

In more recent years, the setting of the monument has been affected by the proximity of the A303 road between Amesbury and Winterbourne Stoke. In early 2003, the Department for Transport announced that the A303 would be upgraded, including the construction of the Stonehenge road tunnel. The controversial plans have not yet been finalised by the government.