Stonehenge is the culmination of a series of building projects spanning a period of around 1,500 years. Opinions surrounding the exact time-scale are constantly evolving and changing, so much of the information presented in this overview should be regarded as a summary of current opinions rather than as a definitive timeline.

The first human activity at Stonehenge can be traced to around 3100BC. At this time, a circular bank and ditch enclosure was constructed from chalk, measuring around 110 metres in diameter. A large opening was left in the north east quadrant, and a smaller opening left to the south. Inside this enclosure, excavations have revealed a ring of 56 pits known as the "Aubrey holes" (named after the 17th Century antiquarian believed to have first discovered them). These holes are round pits with steep sides and flat bottoms, and each measures around a metre in diameter. It's believed that these pits originally held standing posts forming a timber circle. Shortly after completion, this early monument was abandoned for another 500 years.

Around 2600BC, the wooden posts were replaced with up to 80 Welsh bluestones. Conventional theories hold that these stones were transported from the Prescelli Mountains in Pembrokeshire, utilising a series of rollers, sledges and rafts. Each stone weighed around 4 tonnes, and rose to a height of around 2 metres. Once on site, they were erected inside the henge. It is unclear whether all the retaining sockets have been discovered, so some theories suggest that the stones formed two semi-circles, while others suggest two complete rings. The north eastern entrance was widened to align directly with the midsummer sunrise and midwinter sunset. Sometime during this phase, the avenue was also added - a parallel pair of ditches and banks running for 3km from the main monument down to the River Avon. It has been suggested that this was used as a ceremonial approach to Stonehenge from the river.

Around 2500/2400BC, 30 huge sarsen stones were brought on site. These sandstone blocks each weighed in the region of 25 tonnes. These were used to replace the earlier bluestone arrangement. These were erected as a 33 metre diameter circle topped with a further 30 lintel stones. Five trilithons - pairs of uprights topped with lintels - formed a horseshoe within.

At a later phase, the bluestones were re-erected as an outer ring and horseshoe, replicating the layout of the inner sarsens. It is believed that this stage was never completed, as some retaining holes were prepared, but apparently never used.

Around 2280 to 1930BC, another phase of building took place. The bluestones were arranged in a circle between the two rings of sarsens, and also as an oval at the centre of the inner ring. At some point duting this phase, the north eastern section of the bluestones was removed, creating a horseshoe shape mirroring the central sarsen trilithons.

The last construction activity took place around 1600BC. Two concentric circles were dug outside the sarsen circle, suggesting that outer stone rings may have been planned. However, these holes were never occupied, and it would appear that whatever plans the builders had were abandoned prior to completion.

Stonehenge survived throughout the centuries, developing a powerful place in English folklore. By the early 20th Century, it was in a ruinous state, and a national appeal resulted in work being undertaken to restore its setting and re-erect a number of fallen stones. In 1928, the site was purchased by the National Trust. Further restoration work was carried out in 1958, when three sarsens were re-erected and set in concrete. Finally, in 1963, another sarsen was re-erected after it fell, and a further three sarsens were set in concrete.

Today, Stonehenge is one of Britain's top tourist attractions. Coaches constantly ferry large numbers of visitors to and from the stones all year round. Access is expensive and strictly controlled, with visitors being confined to designated paths. The large crowds make it difficult to get a true sense of the site - a situation exacerbated by the surrounding chainlink fencing, intrusive visitors centre, and the busy road that cuts the henge off from the avenue leading down to the River Avon. Finally, the sight of the A303 in the near distance drives one last nail into the coffin, making a visit to Stonehenge a fairly dismal experience. It is extremely difficult to recommend this monument in its present setting.

For the determined visitor, it is possible to arrange private out-of-hours access for small parties at fairly reasonable rates. During such visits, it is possible to approach the stones without being limited to the designated paths. However, current English Heritage plans involve the removal of the surrounding fencing and the closure of the adjacent road, significantly restoring the monument's original setting. For those with the patience to await this development, this may present the best alternative.

Stonehenge has a rich history, and plays an important role in English myth and legend. It is also intertwined with modern cultural developments, serving as a focus for neo-pagans, neo-druids, hippies, travellers and various other fringe groups. For many years, it served as the setting for the Stonehenge Peoples' Free Festival - which came to an abrupt halt in 1985 when the police brutally attacked a convoy of new-age travellers in an encounter that became known as "the battle of the beanfield". Such events serve to further immortalise Stonehenge, ensuring that its mythology will continue to evolve along with the tapestry of British society.