Summer solstice © Captain Skyhigh/Getty Images
The ancient monument of Stonehenge has fascinated people for centuries. Estimated to have been built between 3000 and 2000 BCE in the English county of Wiltshire, its large standing stones remain an enigma. Exactly why and how this massive stone circle was built are still debated. What we do know, is that it was done without metal tools or the use of wheels—and some of those stones were moved more than 150 miles.