The ancient Nabataean city at Petra is one of the most amazing places I have ever visited and I regret having had only one day (and a rainy day at that) in which to explore this vast and magnificent site. I highly recommend visitors consider spending an extra day or two here.
By the 4th Century BCE, Petra was becoming the center of Nabataean (an Arab people) culture. Because of its location, Petra developed into an important trading center and merchants from many cultures crossed paths within the city. Petra lay at the intersection of two major trade routes: one running north and south between Syria and the Red Sea and the other running east and west between the Persian Gulf and the Mediterranean Sea. The Nabataeans thus controlled the lucrative trade in Indian silks, spices, incense and African ivory and they were able to collect steep duties on these precious goods. In addition, they collected fees for protecting the caravans from bandits.
In 106 CE, the Emperor Trajan annexed Petra into the Roman Empire and made it part of the Province of Arabia. The city continued to thrive for several hundred more years. In the 4th Century CE the city began to decline as trade routes shifted and by the 8th Century Petra was all but abandoned. Many of the structures we see today served as tombs and were carved out of the sandstone cliffs.
Petra was "rediscovered" a thousand years later in 1812 by Swiss explorer Johann Ludwig Burckhardt who disguised himself as a Moorish trader to travel through the area. In more recent times, the narrow canyon known as the "siq" and one of Petra's grandest carved monuments, known as the "Treasury," were featured in the 1989 movie, Indiana Jones and the Last Crusade, starring Harrison Ford and Sean Connery.