The ancient site of Stonehenge is a Mecca for tourists, Pagans and Druids and each year, on Midsummer's Eve, thousands of people gather around the stone circle ready to watch the sun rise on the longest day of the year. But despite speculation nobody knows exactly why the stones are there...

There is nothing quite like Stonehenge anywhere in the world and for 5,000 years it has drawn visitors from far and wide.

Nobody knows why hundreds of people struggled over thousands of years to build the monument, but visitors from all over the world come to marvel at this amazing feat of engineering.

Stonehenge was built between 3,000BC and 1,500BC. It is arguably the most sophisticated stone circle in the world but before it was there, the whole of Salisbury Plain was a forest. Over centuries the landscape changed to open chalk downland. What you see today is about half of the original monument, some of the stones have fallen down, others have been carried away to be used for building and over centuries visitors have added their damage too.

It was quite normal to hire a hammer from the blacksmith in Amesbury and come to Stonehenge to chip bits off many years ago, but of course this is no longer permitted.

The ditch around Stonehenge would have been dug using animal bones and deer antlers to loosen the underlying chalk. The shoulder blades of oxen or cattle were used as shovels to clear away the stones. Excavations of the ditch have recovered antlers that were left behind and after their age was tested it was revealed that the first henge was built over 50 centuries ago.

In the 17th century a number of holes were also discovered at the site. These were dug to hold wooden posts, just as later more holes were dug to hold the stone pillars However, the first stage of Stonehenge, built around 5,050 years ago, was a wooden post circle surrounded by a deep ditch and bank.

Around 2,500BC, 2,400 years before the Romans set foot in Britain, the original wooden structure was rebuilt, this time using stones. The smaller stones are bluestones and came from the Prescelli Mountains in Pembroke, South Wales. They were dragged down to the sea, floated on huge rafts and brought up the River Avon, then they were dragged over land to where they are today. This is an amazing feat considering each stone weighs about five tons.

After the second phase there was no more work on the site until about 2,300BC, when what you can see today was first created. The bluestones were dug up and rearranged, this time using even bigger stones from the Marlborough Downs. These giant sandstones, or Sarsen stones, as they are now known, were hammered to size using balls of stone known as `mauls'.

Even today you can still see the marks where the stones were dragged across the site. Each pair of stones was heaved upright and linked on the top by the lintels. To get the lintels to stay in place they made joints in stone, linking the lintels in a circular manner. This was all cleverly designed on the alignment of the rising of the mid summer sun.

The big mystery, and one nobody knows the answer to, is how they managed to get the stones to stand upright. It required sheer muscle power and hundreds of men to move one of these megaliths, the heaviest of them weighing around 45 tons. There are some wonderful myths and legends and you can hear them all on the audio tour at Stonehenge.

Opening times: Mar 16-May 31 &

Sept 1-Oct15 9.30am-6pm; Jun 1-Aug 31 9am-7pm; Oct 16-Mar 15 9.30am-4pm.

Prices: Adults £5.20; child £2.60; concessions £3.90; family tickets £13.

Did you know?

Stonehenge was constructed in three phases

It is estimated that over 30 million hours of labour were spent on it altogether

Speculation on why it was built range from human sacrifice to astronomy

Stonehenge was declared a World Heritage Site in 1986

It is thought the name Stonehenge originates from the Anglo-Saxon period, the old English word `henge' meaning hanging or gibbet, so it literally means `the hanging stones'.

The Stonehenge Project will rescue the site from the noise and clutter of the 21st century. Roads will be removed or tunnelled and ploughed fields returned to open grassland. A new world-class visitor centre is also planned.