The Secret Of Stonehenge

On a windswept English plain, the colossal ediface of Stonehenge looms as one of the ancient world's most remarkable structures - and one of history's most inscrutable riddles. Who were the Ice Age barbarians that laid out the site's first wooden posts more than 10,000 years ago? What "primitive" technology could have created the henge's increasingly massive stone structures? And most baffling of all, why was Stonehenge built at all?