Stonehenge

Stonehenge is a prehistoric World Heritage Site of megaliths eight miles (13 kilometers) north of Salisbury in Wiltshire, England. It was built between 3100 BC and 1550 BC, and was in use until the Bronze Age. The monument is made of a henge, with standing stones in circles. It is probably the most important prehistoric monument in the whole of Britain, and has attracted visitors from very early times.
Building Stonehenge
Stonehenge was built in three stages. Most of the construction took place between 2640 and 2480 BC.
The first stage started around 3100 BC. During this stage, people dug a circular ditch and a ring of 56 pits, known as Aubrey Holes.
The second stage started around 2100 BC. During this stage, the Stonehenge builders brought huge pillars of rocks from Southwestern Wales and erected them into concentric circles around the centre of the site. This double circle was never completed, and it was dismantled during the third period of construction.
The final stage probably ended before 1500 BC. During this period, the monument was remodeled. Its builders erected a circle of 30 upright stones, weighing up to 50 tons each, capped by ring of stone lintels. These enclosed a horseshoe-shaped formation of five pairs of upright stones, each pair capped with a stone lintel.
Using DNA analysis, scientists have discovered that the Stonehenge builders originally came from what is now Turkey.
History
Bluestones
The first stone circle was a set of 'bluestones'. These stones are made of dolerite, an igneous rock.
The Stonehenge builders dug holes that held up to 80 standing stones (shown blue on the plan). Only 43 of these can be traced today.
There are several theories about how these bluestones arrived at Stonehenge. The long-distance human transport theory says the Stonehenge builders brought the bluestones from the Preseli Hills in modern-day Pembrokeshire, Wales - 160 miles (260 km) away from Stonehenge. In 2011, a megalithic bluestone quarry was discovered at Craig Rhos-y-felin, near Crymych in Pembrokeshire. This supported the long-distance human transport theory.
Another theory is that the Irish Sea Glacier brought the stones close to Stonehenge. However, there is no evidence of glacial deposition within southern central England. For that reason, this theory has less support than the long-distance human transport theory.
Sarsen stones
Later, around 2400 BC, the Stonehenge builders brought thirty huge grey sarsen stones (sandstone blocks) to the site. They 'dressed' (worked on) the stones and gave them mortice and tenon joints. They erected these stones in a circle 33 metres (108 ft) in diameter, with a ring of 30 lintel stones resting on top. They fitted the lintels together using another woodworking method: the tongue and groove joint. They arranged the remaining bluestones in an inner circle. Each standing stone was about 4.1 metres (13 ft) high by 2.1 metres (6 ft 11 in) wide, and weighed about 25 tons.
The stones may have come from a quarry about 25 miles (40 km) north of Stonehenge on the Marlborough Downs. It is also possible that they were collected from a "litter" of sarsens on the chalk downs, which are closer. The modern Stonehenge consists entirely of original stones (some of which have been replaced in upright position).
Neighbouring sites
There are also several passage tombs and many tumuli nearby.
Stonehenge has a number of satellite structures which are part of the 'ritual landscape':
Bluehenge/Bluestonehenge: a new discovery, one mile to the southeast.
Durrington Walls: a Neolithic settlement two miles northeast of Stonehenge.
Normanton Down Barrows: a Neolithic and Bronze Age barrow cemetery.
Stonehenge Avenue: leads two miles from Stonehenge to Bluehenge on the River Avon.
Stonehenge Cursus: the largest monument in the area, not easily visible on the ground.
Woodhenge: found in 1925 by an aerial survey. It had a henge and a wooden circle.
Function
No one knows who built Stonehenge or why they built it. During the summer solstice, the sunrise lines up with some of the stones in a particular way. This suggests that the arrangement of stones may work as a calendar. In Egypt and South America, similar ancient buildings can be found. They also show the time of the solstice.
Some scientists believe that early people were able to foretell eclipses of the sun and the moon based on their positions in relation to the stone monument. The site may have served as an observatory where early rituals or religious ceremonies took place on specific days on the year.
Stonehenge itself is owned by the Crown and managed by English Heritage. The surrounding land is owned by the National Trust.
The World Heritage Site includes Avebury and Stonhenge together, though they are quite distinct.