Britain's Stonehenge is yet again a source of fascination ahead of the winter solstice

LONDON — It's that time of year when crowds of pagans, druids, hippies and tourists head to Stonehenge in Britain to celebrate the winter solstice, with the shortest day and the longest night in the Northern Hemisphere.

Thousands are expected on Saturday at the megalithic circle on a plain in southern England as the first rays of sun break through the giant stones that make up one of world’s most famous prehistoric monuments.

Rain has been forecast but there is no doubt it won't be able to drown out the drumming, chanting and cheering.

Beyond the fascination of the ritual, the eternal question may still linger in the back of the minds of many visitors: What was the real meaning and purpose of Stonehenge?

The site has been the subject of vigorous debate, with some theories seemingly more outlandish, if not alien, than others.

This year, those gathering will have something new to discuss.

In a paper published in the journal Archaeology International, researchers from University College London and Aberystwyth University say that the site on Salisbury Plain, about 128 kilometers (80 miles) southwest of London, may have had some unifying purpose in ancient times.

They base that on a recent discovery that one of Stonehenge’s stones — the unique stone lying flat at the center of the monument, dubbed the “altar stone” — originated in Scotland, hundreds of miles north of the site.

What was surprising was that it came from so far away. It was long known that the other stones come from all over Britain — including the so-called bluestones, the smaller stones at the site that came from Preseli Hills in southwest Wales, nearly 240 kilometers (150 miles) away.

That varied geology is what makes Stonehenge unique among over 900 stone circles in Britain.

“The fact that all of its stones originated from distant regions ... suggests that the stone circle may have had a political as well as a religious purpose," said lead author Professor Mike Parker Pearson from UCL's Institute of Archaeology.

It may have served as a “monument of unification for the peoples of Britain, celebrating their eternal links with their ancestors and the cosmos,” Parker Pearson said.

Whatever its original purpose, Stonehenge today retains an important place in Britain's culture and history and remains one of the country’s biggest tourist draws — despite the seemingly permanent traffic jams on the nearby A303 highway, a popular route for motorists traveling to and from the southwest of England.

Stonehenge was built on the flat lands of Salisbury Plain in stages, starting 5,000 years ago, with the unique stone circle erected in the late Neolithic period, about 2,500 B.C.

English Heritage, a charity that manages hundreds of historic sites, including Stonehenge, has noted several explanations — from the circle being a coronation place for Danish kings, a druid temple, a cult center for healing, or an astronomical computer for predicting eclipses and solar events.

So as far as symbolism and unification go — maybe Stonehenge really was a Mount Rushmore of its day?