Mind-Blowing Discovery of the Day: Angkor Wat Was Much Larger Than We Ever Imagined

Few visitors to the temples at Angkor Wat are unimpressed. But, as a team of international archaeologists recently discovered, the visible buildings represent merely a portion of a formally planned urban environment whose existence has been hidden beneath the jungle for a thousand years.

Using lidar, the aerial mapping tool that is revolutionizing the search for lost cities, the team uncovered a medieval cityscape "without parallel in the pre-industrial world." Lidar, which uses lasers to detect hidden variations in topology (it works like radar), can discover shapes invisible to the human eye. Even in this heavily trafficked area, the remnants of a 13-square mile city, complete with an orthogonal grid of streets and canals, were not visible until now.