PetraThe ancient Nabataean red-rock temples and tombs at the UNESCO World Heritage Site of Petra truly embody that overused word mysterious. A few hints of the people who constructed this city in the 3rd century B.C.E. can be found in ancient texts, but relatively little is known of them. After the Nabataeans were conquered by the Romans, Petra declined rapidly. To this day, this city of finely chiseled sandstone and a sophisticated water-management system spread over some 1,000 square kilometers (400 square miles) hasn't given up its secrets to archaeologists. As you walk the site or head up to its higher portions on a camel or donkey, the magic of Petra is undeniable even if much of its history is lost.