The Hanging Garden of Babylon is the only one of the seven wonders of the ancient world for which no archaeological evidence has ever been found. Centuries of digging have turned up nothing, and many people assume it never existed. But has everyone simply been looking in the wrong place? Oxford academic Stephanie Dalley has decoded an ancient, long-overlooked text in the British Museum and now believes that the gardens were built by another man, in another time, in another location. She travels to war-torn northern Iraq to gather evidence to support her controversial new theory and try to solve this ancient mystery. Part of Channel 4's Secret History strand, which showcases the best historical journalism.