More than 4,000 years ago in what is now England, prehistoric people began an astonishing construction project. The builders had no metal tools, horses, or wheels. But somehow, for some unknown reason, they gathered massive 20-ton stones and arranged them vertically in a circle. Then they managed to drag the 2-ton stone blocks across 175 miles and added them to the monument. Today, we call this strange and awe-inspiring stone circle Stonehenge.
Recently, photographer Martin Edström partnered with National Geographic to capture Stonehenge in augmented reality, or AR. That way, people around the world can use an app on their phone to see it up close in 3-D, like a digital tour.