Petra (greek for rock) was the principal city of the Nabateans and flourished under the Seleucid rulers and later the Romans, Placed strategically on the trade routes to Arabia and Far East it controlled the spice trade in the late antiquity. Petra was famous for its cut-in rock architecture and hydraulic engineering. View of the approach to "The Treasury". Jordan. Nabatean circa 1st C BC. Petra, Wadi Araba.