Stonehenge is probably the most recognisable and enigmatic stone circle in Britain. The structure has fascinated people for centuries, and there are many theories as to what purpose it was put to by ancient man. Stonehenge has suffered over the years from trophy hunters, and the wear and tear of many visitors. The structure is now surrounded by a fence, which although not aesthetically pleasing is helping to preserve the monument from erosion.

Archaeologists have agreed that Stonehenge was built in four distinct phases: The first phase began around 3200BC, and consisted of the henge earthwork enclosing a wooden building, which according to Aubrey Burl may have been a charnel house. An outlying stone, the heel stone was also set in place. Around 2400BC 56 pits known as the Aubrey holes after John Aubrey, were dug around the inside of the ditch. Their purpose is unclear but finds of human bones and stone mace heads suggest ritual offerings.

The second phase began around 2200BC, blue dolerite stones with their origin in the Prescilly mountains in Wales, were erected in two concentric circles. An earthen avenue was also created. It is not clear whether the Welsh stones were transported from Wales, or were already in the local area due to the movements of glaciation.

The third phase began around 2000BC, first the blue stones were removed, and the large sarcen blocks erected in the pattern still visible today. The sarcen stones vary in weight from twenty to fifty tonnes, and were quarried and transported from the Marlborough downs eighteen miles away. They were smoothed and finished to precision with stone hand tools, and locked together with mortis and tennon joints. The upper hanging stones in the trilithons are a ball and joint affair. The balls are clearly visible on the taller stones, in the places where the lintels have fallen over the centuries.

The fourth phase began around 1600BC, when the blue stones were re-erected from an unknown storage place to the centre of the great horseshoe.

Stones in the four directions were carved with axe heads and depictions of other weapons, and the stone known as the altar stone was also erected in the centre of the circle, it may have once stood upright.

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