Petra
Jordan · not visited
Everyone photographs the facades. The achievement is the plumbing: a perennial water supply engineered out of a canyon that gets almost no rain.
- Latitude
- 30.3285° N
- Longitude
- 35.4444° E
- Nabataean capital
- c. 1st century BCE
- Hidden platform, 2016
- c. 56 × 49 m
- Open questions
- 4 logged
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Beneath the most famous facade
In 2024 a joint Jordanian and American team, with rare permission from the Jordanian government, dug beneath the Treasury at Petra. They had located a hidden tomb with remote sensing, and when they opened it they found twelve complete skeletons and objects of bronze, ceramic and iron, about 2,000 years old. Two other hidden tombs with partial skeletons had been found beside the structure in 2003. Pearce Paul Creasman, one of the leaders, said there is much we have yet to learn about the Treasury.
Two centuries after the Swiss traveller Johann Ludwig Burckhardt reached the city in 1812, the best-known building in Petra is still not well understood.
What is actually there
A city carved into rose-coloured sandstone cliffs in southern Jordan, approached through the Siq, a natural gorge over a kilometre long and in places only a few metres wide, which opens without warning onto the facade of Al-Khazneh.
It was the capital of the Nabataeans, an Arab people who controlled the incense and spice routes running from southern Arabia to the Mediterranean, and who grew wealthy enough by the first century BCE to carve monumental architecture out of a desert canyon. Rome annexed the kingdom in 106 CE. The city declined after earthquakes in the fourth and sixth centuries, and by the medieval period it was known mostly to local Bedouin communities.
The thing that actually built Petra
The facades get the attention. The water system is the achievement.
This is a capital in a place that receives almost no rain.
Charles Ortloff's 2005 analysis in the Cambridge Archaeological Journal describes a system that drew on all available water and balanced reservoir storage with continuous-flow pipelines to keep supply steady across the year. One detail corrects a common idea: the designers ran water in open channels within the piping at maximum flow, which Ortloff links to avoiding the leakage of pressurised systems. Sequential settling basins treated water for drinking. He argues that this hydraulic skill helps explain the city's centuries of prosperity.
The same flash floods the system had to manage are still dangerous. The Siq has flooded fatally in modern times.
The sky here
In 2013 Belmonte, González-García and Polcaro published a statistical analysis of the orientation of Nabataean sacred monuments in the Nexus Network Journal. From the abstract and the publisher's summary: the Urn Tomb shows a series of solstitial and equinoctial alignments, Ad Deir produces a set of light and shadow effects that are perhaps connected to Nabataean mythology, and the authors conclude that astronomical orientations were often part of an elaborate plan, possibly reflecting the astral nature of Nabataean religion.
Note the hedges: perhaps, possibly, might have. I have read the abstract, not the paper, so I cannot tell you what the sample size or the tolerance is. The claim that the sky was a substantial part of Nabataean religion is a serious one, but it is a hypothesis built on orientations, and it needs the full data to be judged.
A facade carved into a cliff is, structurally speaking, the cheapest monumental architecture there is: you are removing stone, not lifting it, and the mountain does the load-bearing. What took real engineering at Petra was invisible, and it was plumbing. What if the reason Petra feels dreamlike is that we are looking at its advertising? These are the surfaces a Nabataean wanted an arriving caravan to see after a kilometre of dark gorge, and they worked then exactly as they work on a camera now.
Why it is worth asking: because the visible and the vital are so far apart at this site, and the choice of what to spend on is a form of evidence. What supports it: Ortloff's engineering, and the sheer volume of carved facades. What speaks against it: carving a facade takes real skill and labour, many facades are tombs and not advertising, and the water system was not hidden, since channels run visibly along the walls of the Siq. What would tell the readings apart: labour estimates for the facades against the water works, and where dedicatory inscriptions are concentrated. What stays unknown is what a Nabataean thought the facades were for.
What is still open
What else is buried?
In 2016 Sarah Parcak and Christopher Tuttle reported a monumental platform found with satellite imagery and drone photography: a paved platform of about 56 by 49 metres with a building roughly 8.5 metres square at its centre, with pottery from the site dated to the mid-second century BCE. It has not been excavated. Its design is unique at Petra and may have been ceremonial. Figures of 80 to 85 per cent unexcavated circulate widely, but I could not trace one to a published survey, so I am not quoting a number. A published map of what has been excavated would answer it.
What was the Treasury actually for?
The name comes from a Bedouin story that the urn held pharaoh's treasure. Archaeologically the building is generally read as a royal tomb or mausoleum, sometimes linked to Aretas IV, but that rests on architectural comparison and not on an inscription. The tombs found below it in 2003 and 2024 show the ground was used for burial, but they do not by themselves date or explain the facade. A dated link between those burials and the building, or an inscription, would help.
Who were the Nabataeans, in their own words?
They appear in the record already established as traders, with no clear archaeological trail of an earlier sedentary phase. The shift from mobile pastoralists to builders of monumental rock-cut architecture happened fast, and the intermediate stages are thinly documented. Nabataean inscriptions exist and the script is an ancestor of Arabic writing, but the corpus is dominated by short funerary and dedicatory texts. Most of what is written about them was written by Greeks and Romans. A longer text in their own voice would change the picture.
Were the monuments laid out by the sky?
The published claims are hedged, and the data behind them is in a paper I have not read. What would settle it is a transparent survey that states in advance which targets count, and tests the result against random orientations.
Sources
- UNESCO World Heritage listing, Petra, inscribed 1985.
- Ortloff, C.R., “The Water Supply and Distribution System of the Nabataean City of Petra (Jordan), 300 BC to AD 300”, Cambridge Archaeological Journal 15(1), 2005, pp. 93 to 109. I read the abstract only.
- Belmonte, J.A., González-García, A.C. and Polcaro, A., “Light and Shadows over Petra: Astronomy and Landscape in Nabataean Lands”, Nexus Network Journal 15(3), 2013, pp. 487 to 501. Link. I read the abstract only.
- Parcak, S. and Tuttle, C., 2016, on the monumental platform found with satellite and drone imagery, as reported by Archaeology magazine and National Geographic, June 2016.
- Smithsonian Magazine, October 2024, on the excavation of a tomb beneath the Treasury, led by Pearce Paul Creasman with Jordanian colleagues.
- Burckhardt, J.L., Travels in Syria and the Holy Land, 1822, the first European account of the site.
Not visited in person. Written from published sources. Last reviewed 12 October 2026.