The final approach is made on horseback. Steep cliffs tower on each side, shutting out the world. For a moment it is as if the last 2,000 years never happened, as if the Nabateans of south Jordan still ruled their far-flung ''caravan kingdom,'' coordinating the spice trade to market towns on the Mediterranean.
Even the horses - ''apathetic nags'' in the delightfully apt phrase of one local guidebook - seem somehow to share in the reverent quiet, with the young Bedouin tenders marching alongside, and the guide on his separate mount a few feet ahead.
Then, suddenly, appears the city of Petra, the Nabatean capital carved into soft pink cliff faces about the time of the birth of Jesus.
Even in the Mideast - competing with the Pyramids, the old walled town of Jerusalem, or the mosques of Istanbul - Petra has no peer in its literally breathtaking ability to surprise.
The first glimpse is the finest: a stately, columned mausoleum that seems, at first, to be free-standing, until the eye focuses on the towering cliff immediately behind.
Then the eye finds a further guidepost: a procession of ancient, indented footholds - scaffolding, Petra style - by which Nabatean stone carvers scaled the rock face to work on their monument. It is as if nature, geography, and modern Mideast politics have all somehow conspired to preserve Petra from all that has come since.
There was one lapse, when a Roman army somehow negotiated its way through the angry range of surrounding hills and cliffs to capture the then-capital of the Nabatean civilization in AD 106. (The Romans' influence had preceded them. The mausoleum at the town's entryway projects a Roman-style facade. An amphitheater deeper into town similarly recalls the empire of the Caesars, and it is thought by some to have been built by the Romans after they arrived.)
But later battles would spare Petra. The ancient trade routes that helped the Nabateans prosper had shifted by the second century AD, and other trade centers, like Palmyra in what is now Syria, took over the business of propelling history forward.
Petra - its ring of mountains stumping the erosive tools of nature better than it had the Romans - slept. And, largely, survived.
Though it would be rediscovered by British archaeology some 1,700 years later , Petra has since managed almost perfectly to survive even the era of air travel and package tours.
The Jordanian government, with merciful slowness, is now developing the site as part of a bid to siphon off tourists from better-known Mideast sites in Israel and Egypt.
The main step taken so far has been unmitigatedly positive: construction of a luxury hotel tucked subtly into a hillside where the paved road from Amman stops and the final, one-mile horse ride down to ancient Petra begins. A room for one person runs about $30 US. An older but comfortable guesthouse nearby is considerably cheaper.
There has been talk of opening an air link to the area from Amman. But at present it's best either to travel the several hours through desert and hill from Amman by private taxi (about $180, round trip, including an overnight stay for the driver) or to take a $30 one-day bus tour that includes lunch.
For those who have an aversion to apathetic nags, guides will in exceptional cases drive visitors into old Petra by jeep. This, unless necessary, makes about as much sense as choosing a snowmobile over a horse sleigh for a Christmas Eve tour of some tiny Swiss mountain village. Most visitors prefer the nags.
For the more adventurous, there is the option of traveling on foot - and of wandering off the imperfectly beaten path to view a series of some two dozen stone towers set amid caves on either side of the descent to the main town.
Even if you're on horseback, comfortable shoes (sneakers, for instance) make sense. You'll want to dismount once you get to the jolting mausoleum that tells you Petra awaits.
The most impressive of the other surviving structures are, similarly, tomb sites. The presumably free-standing residential areas of Petra are gone. But also surviving is a colonnaded road, thought to be Roman, just beyond the amphitheater.
When flashes of the present day intrude on the visitor, it is usually in the form of the Bedouin, who have for many post-Nabatean centuries inhabited the town and its hilly environs.
A stone urn atop the mausoleum at Petra's entryway is full of Bedouin bullet holes - because, legend had it, a treasure was stored within.
And in caves amid some of the town's othermost impressive monuments, some Bedouin still live. Wash hangs outside. Bedouin teen-agers race gaily atop distinctly ''unapathetic'' nags. Other children peddle souvenirs and, even if the visitor is not in the market, offer smiles and a chirped ''Ahlan wa salhlan, '' Arabic for ''welcome.''
For several years, the Jordanian government has been relocating Bedouin from Petra caves to new clusters of small, simple houses nearby. But some Bedouin stay on - uninclined, as one of them explains, to move from dwellings that generations have made home.