The ancient city of Petra, Jordan, was named a UNESCO World Heritage site in 1985 and has more recently been added to the list of New Seven Wonders of the World. Lost to the western world until 1812, the 'rose-red city' with its stunning sandstone architecture carved directly into bedrock is truly impressive.
First constructed by the Nabataeans starting around 200 BC, and later controlled by the Romans (beginning in AD 106), this desert metropolis is noted for an elaborate water management system that allowed the city to thrive for centuries in an arid region while functioning as an important trading hub for the ancient world (Ruben 2003; Ortloff 2005).
Recent non-destructive geophysical investigations of the so-called Upper Market area in the Petra city centre have revealed a range of previously unknown features likely to be related to the water management of the city. A thorough understanding of this system is crucial to knowing how and why the city emerged, expanded to a population of 20 000 residents, and eventually fell into decline.