Learn how Nabataean engineers supplied the desert city of Petra with water more than 2,000 years ago, in this video from NOVA: Building Wonders: Petra. Archaeologists have discovered that underlying the city’s Great Temple is evidence of a citywide water system. However, the nearest spring that could have supplied the city with water is 5 miles away. After conducting a series of tests in the U.S. and taking measurements from Petra, a hydroengineer reveals the Nabataeans’ design solution that enabled them to transport water fast and without leaking from the spring to Petra: a ceramic pipeline with a precise slope of 4 degrees.