On the main caravan routes between the Mediterranean and Arabia - and Asia and the Far East beyond - Petra's magnificent ceremonial buildings were carved into rosy sandstone cliffs surrounding the city. Lost to the desert for hundreds of years, it was rediscovered in the early 19th century by a Swiss adventurer traveling as an Arab among the nomadic Bedouins.
Petra was built by the Nabateans, pragmatic trading people who lived there
from about 600 B.C. to 700 A.D. At its height, in the first century A.D., Petra was home to about 30,000 people. Then it could easily have been as noisy as Manhattan today. The canyons must have fairly roared with the clatter of thousands of camel and donkey hooves and the cries of caravan traders, jubilant after their desert treks, eagerly bargaining in the thronged marketplace.
Petra may have been the first city of skyscrapers, with latter-day cave- dwellers carving their homes up and down the water- and wind-worn mountains. Magnificent tombs, adapting Assyrian, Hellenistic and Roman architecture, loom over the Wadi Mousa, or Moses' river or watercourse,
winding through what was once a magnificent thoroughfare between imposing free-standing buildings.
The Wadi Mousa comes from Ain Mousa, Moses' Spring, one of the sites where Moses is said to have struck the rock that brought forth water for the wandering Israelites.
But the area is also replete with events from more modern history.
A two-hour drive south of Petra is the Wadi Rumm, repeatedly crossed by T.E. Lawrence - Lawrence of Arabia - in his desert exploits during World War I. Arab tribes were posted in Petra to protect Lawrence's gains against counterattacking Turks.
Three hours north of Petra is Amman, the booming capital of Jordan, built on the site of the Roman Decapolis city of Philadelphia. And, in Petra itself, Agatha Christie concocted a murder plot while her husband toiled on a British archaeological dig during the 1930s.
The unremitting rockiness of the region, plus the centrality of stone and rock in the Christian, Jewish and Islamic religions, makes Petra compelling, both symbolically and physically. Dusares, the main god of Petra, was represented by a block of stone; the Hebrews' Jehovah was said to live in a rock called Beth El; in the New Testament, Jesus said he founded his church on a rock; under Islam, the third great monotheistic religion of the ancient Near East, Muslims make pilgrimages to the Kaaba, a black stone block in the center of Mecca.
Petra, which means rock in Greek, began as a city under Nabatean nomads who developed a trading culture that lasted a thousand years by guaranteeing the safe passage of caravans through their desert mountain pass.
The building of Petra was only one practical act of these eminently pragmatic and flexible people, who moved out after a thousand years to shift with the trade routes. The Nabateans' written language was the predecessor of Kufic and Arabic.
Petra's power peaked under early Roman rule in the first century A.D., but the city endured, declining slowly under Roman control as the trade routes changed, finally fading with the Muslim expansion in the seventh century.
When a visitor strolls into Petra, it is as though flowing into a vein of rock; a sympathy with the undulations in the stone gradually emerges. Eons ago, the cart-wide, mile-long and 400-foot-deep canyon entrance to Petra - today called the Siq - was opened by a gigantic fracture that was then whittled and whorled by water and wind. In the Siq, the visitor shrinks, becomes like a drop of water rolling along the dry bed of the Wadi Mousa.
The angle of light is king in Petra. The ideal time to wander through the Siq is early morning, when the sun creeps along the top of the canyon walls like golden mountain goats checking their footing on the steep slopes, testing the contours. The stark silence, softened by the cooing of doves high in the crevices, is marred only by one's own slipping footsteps on the gray, rocky riverbed.
At the last turn in the Siq, through the narrow slit of the canyon walls, enormous pilasters with decorated pediments and capitals suddenly fill the eye. The best-preserved classical Hellenistic monument in Petra, the Khasneh or Treasury, squats implacably at the entrance to the city, described by a poet as "half as old as time." To some, the Khasneh is the high point of Petra: Its carved details are well-preserved, and it is the most accessible of Petra's monuments.
But the awesome scope of Petra can be grasped only by trekking out to the mammoth En Deir, or monastery, far out on the western periphery of the city, overlooking the start of the Great Rift Valley that slices through the Red Sea, Ethiopia and East Africa.
After a two-hour walk from the Khasneh, En Deir appears abruptly around a bend in the rocky path. Nearby is a goatherd woman's cave home, topped by a TV antenna and attended by a fat calico cat, whose coloration reflects the marbled buff, rust, rose and mustard-yellow of Petra's sandstone cliffs.
Around every corner in Petra lurks another wonder, another carved tomb, cave house, Roman column, trace of the Nabateans' complex irrigation system, a Roman amphitheater - all embellished by nature's bizarre erosion of the rock.
Aside from the carved cliff monuments and tombs, most of ancient Petra's free-standing buildings lie buried in the bed of Wadi Mousa, awaiting armies of archaeologists and years of excavation.
Something peculiar happens to depth perception in Petra: The city often looks like a theater backdrop, a mere layer of paint that could be peeled off. The distances are deceptive, the sandstone of the foreground melting against the more remote hills.
In fact, Petra is being "peeled" and desperately needs preservation. The facades of the monuments are rapidly eroding. Softened by wind, rain, freezing and thawing, the sandstone can be rubbed off by hand.
Archaeologist David McCreery, director of the American Center for Oriental Research in Amman, says that a retired American chemist had come to Petra to study preservation techniques. But his method - penetrating the sandstone with poly-vinyl-acetate - failed because water could still soak behind the treated surfaces and in winter would freeze and split off the treated rock.
Although ravaged continuously by the forces of nature, Petra remains relatively unspoiled by tourism, especially at non-peak times. On a cool, sunny winter day in January, Petra is exquisite.