NEW YORK - Across midtown Manhattan this month, you keep running into a poster showing a mountain that seems to part, like stage curtains, to show a Greco-Roman temple. The poster announces an archeological exhibition, Petra: Lost City of Stone, which is at the American Museum of Natural History until July 6. The drawing has a mysterious look, which is right: Mystery clings persistently to Petra, a mountain city 90 km south of the Dead Sea, in a part of the Negev Desert that is now Jordan.
Rose Macaulay, who wrote an eloquent book called Pleasure of Ruins half a century ago, considered Petra the most romantic of all dead cities: "Sumptuous in ornament and savage in environs, poised in wildness like a great carved opal glowing in a desert, this lost caravan city staggers the most experienced traveller." A mountain pass, only eight or nine metres wide and 1.2 km long, leads the way to Petra, the capital of the ancient Nabatean people.
That pass was the key to the city's history, during several centuries of great prosperity and a much longer period of obscurity. You can walk it, as most visitors do, or ride on a horse, but in any case Petra knows you are coming well before you get there.
Two millennia ago, the pass protected it from all but the most powerful intruders. Then, after the Romans conquered Petra and the Nabateans disappeared from history, the same passage kept Petra's existence a secret from the world for some 1,500 years.
Today that twisty trail through the mountains creates a moment of high drama, displaying both nature and culture at their most theatrical. A visitor walks for more than a kilometre, wondering idly how the real Petra will compare with the one illustrated in books. Then there suddenly appears a corner of a tomb, 45 metres high, with Corinthian columns, cut into the side of a mountain. It would be thrilling even if it were grey, but colour gives it a special force, the red sandstone of the architecture changing tone from minute to minute as clouds move across the sky and visitors hurry toward it. (That's the tomb where Harrison Ford and Sean Connery arrive on horseback in Steven Spielberg's Indiana Jones and the Last Crusade.)
There's nothing quite like seeing Petra, but the American Museum of Natural History approximates the experience with a superb collection of some 200 objects, photographs and films.
The best sculptures, ceramics and ancient inscriptions found there have long since been removed to museums for safekeeping, and these are the objects brought together by the American Museum and its collaborator on this occasion, the Cincinnati Art Museum.
A temple wall at Petra held an elaborate limestone sculpture, carved around AD 100, of a Greek goddess displaying zodiac symbols. At some point, perhaps in the catastrophic earthquake of AD 363, the wall fell and the sculpture split in half. One part was discovered in 1937 during a dig sponsored by the Cincinnati Art Museum. It's been among Cincinnati's many Petra treasures ever since. In recent years, the other half has also been recovered, and deposited with Jordan's Antiquities Department. New York has reunited the two parts for the first time in probably 1,640 years.
The Nabateans emerged out of the obscurity of prehistory six or seven centuries before Christ, nomads who settled down when they found the perfect place to build a society. They dominated the camel-caravan route that brought trade goods from China, India and Southern Arabia to the Mediterranean. Ivory passed through their hands, and textiles, as well as cinnamon, frankincense and myrrh. They grew rich, and inventive.
In Petra, which at its height had about 20,000 residents, they developed virtuoso-level engineers who built brilliant water systems and brought an arid landscape
to life. They had architects who designed formal gardens, a colonnaded street, a theatre that held about 8,000, large pools, about 800 tombs, and facades in the style of the Greeks and the Romans. Their sculptors created images of the Greek-derived gods they worshipped.
One massive Hellenistic head provides a highlight of the New York show: He's apparently Dushara, the Nabatean version of Zeus, controller of rainfall and the harvest. His upward gaze, parted lips, laurel wreath, tight curls and short beard all make him unmistakably Greek.
The Romans under the Emperor Trajan took Petra in 106, Byzantine Christians succeeded them (and built at least one huge church around 350) and Muslims conquered it in the seventh century. The Crusaders controlled it for
a time, and built a mountaintop castle, but in the 12th century Saladin drove them away. Having been a crucial trading centre, it grew so insignificant that it disappeared from the world's maps, known only to the Bedouin who inhabited it (and they preferred to keep it a secret). It was little more than a rumour till 1812, when a Swiss traveller, Johann Ludwig Burckhardt, disguised as an Arab, made his way there. In 1829, he told the world about it in his book, Travels in Arabia.
Today Petra still retains many secrets. Perhaps one-twentieth of it has been explored. But the speed of the discovery process has been increasing. Traditional archeology, which included drawing conclusions about below-surface objects by taking core samples with an auger, was at once painfully slow and potentially destructive; it could wreck a site while revealing it. That has been partly replaced, at Petra and many other places, by archeo-physics. Ground-penetrating radar, dragged across a site, creates three-dimensional maps of buried objects by sending pulses downward, then analyzing the reflections that return to the surface; on laptop computers, archeologists can study hidden objects as soon as the radar reports them.
As a result, the Petra described in New York this season differs notably from the actual Petra I visited only six years ago. In 1998, an immense pool complex was found. In 2000, the archeologists discovered, to everyone's surprise, a Nabatean villa outside the safety of the mountain pass. And this year they came across rock-cut tomb-like spaces in the ground beneath the pillars we see first from the pass, creating new questions about the meaning of this icon -- further proof that we are living in one of the great ages of archeology.