Petra, where breath-taking architecture is carved into rose-colored sandstone cliffs, is a three-hour drive south of Amman, Jordan.

Accessible only through a narrow gorge, Petra was one of the most easy to defend cities of the ancient world. Its leaders became rich through trade, good water management and by exacting tolls from caravans. Petra's glory days were in the century before Christ's birth. When Rome annexed it in the second century, Petra had about 30,000 residents.