Petra is certainly the ideal place to set an archaeological adventure.
That entrance - the Arabs call it a siq - is extraordinary.
It's a 1.2 kilometres long passage through towering 100m red rock walls, at times only a couple of metres wide, carved by wind and rain into an incredible array of stone sculptures.
It would have been easily defendable and 2000 years ago it provided a secure base from which the Nabateans, a tribe of Bedouin, were able to develop a trading empire embracing the known world.
The city they called Rikim - Petra came later from the Graeco-Roman word for rock - is even mentioned in Chinese records, so great was its influence.
Unfortunately, its success proved its downfall. The Romans got fed up with the Nabateans making all the trade profits and launched a compulsory takeover.
It is an eerie experience to walk that narrow chasm, imagining the caravans of camels laden with gold and spices that trod the same route so long ago under the watchful gaze of those looming cliffs.
Signs of the sophisticated society the Nabateans built in their rocky home are everywhere as you wander down the siq.
Each of the smaller ravines leading into the main passage was once dammed, partly to reduce the risk of flash floods - "if it rains," our guide Yousef Hilo tells us cheerily, "you've got about eight minutes to get out" - and partly to collect drinking water.
On either side are the remains of the covered culverts used to take water to the city.
Where the siq broadens a little are carved niches in the rock to take statues of gods.
And halfway down is the shrine to the chief god, Dushara, still bearing his image, a simple rectangle with square eyes and a straight line for a nose.
"He didn't need a mouth," explains Yousef, "because his power was so great he did not have to speak."
Because I collect such things, I tried to buy an image of Dushara.
I eventually got a small ceramic replica of a plaque in the Nabatean Museum, at the entrance to Petra, showing a figure with a mouth and carrying a dedication from Hayan son of Nibat "to my god".
"They say now that is Dushara," said Yousef, an enthusiastic archaeologist, "but it is not. It is one of the lesser gods who had to speak to make his will known."
Behind the image is a cave carved into the rock where the guardian of the god lived.
Was he a priest?
"No," says Youssef.
"More of a salesman. He sold frankincense for travellers to offer to Dushara. The Nabateans were great business people."
Dushara may have been a remarkably unostentatious god but the Nabateans definitely were not.
The buildings they cut into the sandstone cliffs are amazing.
The Treasury - where Indiana Jones sought the Holy Grail - has been much-photographed, but it still has tremendous impact when you look down the narrow red walls of the siq and see its magnificent facade rising 43m in the cliff opposite.
It was not a treasury, but one of the royal tombs, although it does look a bit like the Bank of England carved in solid rock.
And, although it probably hasn't held the Grail, it does carry a wonderful mix of religious symbols which provide further evidence of how widely Nabatean interests spread.
In the centre at the top, a little spotty after being shot-up by bored locals, is Isis, the Egyptian goddess of death.
On either side of her are two ferocious Amazons, not as you might think followers of New Zealand's Lucy Lawless, but Greek daughters of Zeus.
And at the bottom are the Roman gods Castor and Pollux, each leading a corpse on a horse.
You can't actually go inside the tomb, which is guarded by an impressively uniformed Bedouin policeman, but it appears to consist of plain rooms carved into the rock, all the contents having been stolen by the Romans long ago.
The Treasury sits where the narrow entrance broadens into a wider canyon, providing space for those who hawk souvenirs and camel rides, and all around it are more tombs carved into the rock.
There are more than 500, those with impressive facades having been made for royalty, the simple holes for the common people.
The royal tombs are huge works of art, mostly 40 or 50m high and equally wide, carved in an amazing range of styles, some with pillars and others with obelisks, some with figures and others fairly plain. And all cut into the huge cliffs of red stone.
It is hard to imagine today, but these stunning sculptures were not the focal point of the city of Rikim.
They never lived in the buildings they carved in the rock. Why?
"The Nabateans were too rich to need to live in caves," says Yousef, with maybe a little hauteur.
"They built themselves magnificent homes."
The remains of those can be seen further down, where the canyon widens, and a few surviving colonnades and vast piles of stone blocks show where once there were palaces, temples and houses.
However, the people are less sniffy these days about using holes in the rock. We had some refreshing mint tea in a cave cafe while the owner sucked enthusiastically on his nargila water pipe.
I also had the interesting experience of using a toilet built into a cave while the custodian proudly showed a couple of female tourists round the facilities.
Other caves are used as souvenir shops, reminding Yousef that this is an ancient tradition.
"We recently found a 2000-year-old souvenir shop," he says, "where the Nabateans made fake gold artefacts to sell to visitors."
Despite that, and despite a warning that people at Petra were more aggressive in pushing their wares than is usual in Jordan, we found them quite charming.
During the long trek up to the biggest of the monuments, the magnificent monastery, the youngsters selling donkey rides did so with considerable wit.
"Taxi," they cry to sweating, red-faced visitors struggling up the pathway with its 800 steps cut into the rock.
"Latest model. Air-conditioned. Supercharged."
And the women on the little stalls along the route, selling carved camels, Roman coins and ancient oil lamps, are equally amiable.
"Maybe on the way down," I tell one.
"Okay," she says, "I don't sell to anyone until you come back."
Sure enough, when I return she hasn't forgotten. "Hey, mister, you said on the way down. I waited just for you."
It's a hefty climb but worth it. The 50m-high monastery with its incredible facade was built by the Nabateans as their temple and appears to have been a pilgrimage site. It got its present name in the 4th century when it was used as a monastery by Coptic Christians who painted crosses on the back wall.
Struggle up a little further and there are stunning views over the rocky mountains and rugged canyons all the way to the Dead Sea.
On one amazing vantage point is a small stall, selling cold drinks and souvenirs, proudly bearing the name The Last Shop at the End of the World.
The proprietor periodically plays the flute to lure customers from a rival stall on a similarly spectacular peak a short distance away.
Looking over the arid wasteland stretching in all directions it isn't too hard to imagine it truly being at the end of the world. In any event, it is the end of the Petra trail.
From there it's a 5km trek under the broiling sun back through those amazing rock carvings and that mysterious siq to the entrance. The horse ride over the final stage comes as a welcome relief, although my cowboy seems disgusted that I decline the chance to gallop.
As I dismount at the Petra Visitor Centre, trying desperately to look like Indy, I can't help wondering if the folks here remember the great relic hunter.
Then a sign stands out amid the clutter of shops and stalls, cafes and museums: "Indiana Johnes Snack Shop".
How can I resist?
Jim Eagles and Alan Gibson went to Jordan as guests of United Travel and Ancient Kingdoms Holidays.
