In the Sahara Desert in Egypt lie the oldest known astronomically aligned stones in the world: Nabta. Over one thousand years before the creation of Stonehenge, people built a stone circle and other structures on the shoreline of a lake that has long since dried up. Over 6,000 years ago, stone slabs three meters high were dragged over a kilometer to create the site. Shown above is one of the stones that remains. Little is known about the ultimate purpose of Nabta.