Petra is a rock-cut city in southern Jordan, carved into rose-coloured sandstone cliffs beside the town of Wadi Musa in Ma'an Governorate, and it was the capital of the Nabataeans, an Arab trading people who called it Raqmu (written rqmw in their inscriptions). Settled from the 4th century BCE and at its height in the 1st century CE, it is best known for Al-Khazneh, "the Treasury", a royal tomb façade cut straight into the cliff, and for a water system that let a city of roughly 20,000 people thrive in a desert.
Petra matters because it is one of the clearest cases of an ancient people doing something that still looks improbable today, and leaving enough evidence behind to show how they did it. Tool marks, dated pottery, inscriptions and surviving dams make it a useful benchmark for every other "who built this and how" question.
Who were the Nabataeans?
The Nabataeans were an Arab people of the northern Arabian desert who grew rich by controlling caravan routes, and their first securely dated appearance in history is in 312/311 BCE. In that year Athenaeus, an officer of Antigonus I Monophthalmus, raided them; the episode is preserved by the Greek historian Diodorus Siculus, who describes them as a strong tribe of "some 10,000 warriors", pre-eminent among the nomads of Arabia.
Their wealth came from trade in frankincense, myrrh and spices from southern Arabia, and in bitumen from the Dead Sea. UNESCO describes Petra as a major caravan centre linking Arabia, Egypt and Syria-Phoenicia.
They normally spoke a form of Arabic but wrote formal texts in Aramaic, and their own cursive form of the Aramaic script is widely accepted as the ancestor of the Arabic alphabet.
Their religion centred on Dushara, the chief god and royal patron of the kingdom, and the goddess al-'Uzza. In the early period the gods were represented by plain standing stones or blocks, known in scholarship as baetyls, rather than by statues; Hellenistic-style statues came later.
When was Petra built and who lived there?
Petra was built in stages over several centuries rather than all at once. The Nabataeans settled the basin from the 4th century BCE, it was serving as their capital by the 2nd century BCE, and the city reached its peak in the 1st century CE, largely under King Aretas IV, who reigned from 9 BCE to 40 CE. Estimates for the population at that height are around 20,000 people.
Most of the famous façades belong to that 1st-century peak. Visitors mostly see the funerary side of Petra, because tombs cut into living rock outlast masonry, but the city also had a colonnaded street, temples, markets and houses. The Great Temple was excavated and restored between 1993 and 2000 in a project funded by Brown University.
What is Al-Khazneh, the Treasury?
Al-Khazneh is a monumental tomb façade carved directly into the cliff at the end of the Siq, the narrow gorge that serves as Petra's main entrance; it was a royal mausoleum, not a treasury. Current scholarship places it at the beginning of the 1st century CE, in the reign of Aretas IV, and it is often suggested that it was built as his tomb, although no inscription names its occupant.
The façade stands roughly 37 to 40 metres high (published figures vary) and about 24 metres wide. Its Hellenistic design includes Corinthian columns, a central round pavilion (tholos), the twins Castor and Pollux and dancing Amazons carrying double axes. Inside is a plain main chamber with smaller side rooms.
The name "Treasury" comes from a local Bedouin legend that the stone urn crowning the tholos held hidden treasure. The urn is pocked with bullet marks, which the Jordanian authorities attribute to people who believed the legend and tried to shoot it open. It is solid rock.
The dating debate and the 2024 tomb
For a long time the Khazneh's date was genuinely disputed, with proposals spread across several centuries. Archaeologist Laurent Tholbecq summed up the present position in 2024: long disputed, now placed in the first quarter of the 1st century CE.
New evidence came in 2024. A team working with Jordan's Department of Antiquities and the Petra Development and Tourism Region Authority, led by Pearce Paul Creasman of the American Center of Research (ACOR) with geophysicist Richard Bates of the University of St Andrews, used ground-penetrating radar and electromagnetic surveys to locate a sealed tomb beneath the Treasury's forecourt. Excavation revealed the remains of 12 people. One skeleton was found with the upper part of a ceramic jug dated to the 1st century BCE. Sediment analysis by Tim Kinnaird of St Andrews dated the construction of walls inside the tomb to between the mid-1st century BCE and the early 2nd century CE. St Andrews announced the find on 15 October 2024.
An adjacent tomb had been excavated in 2003. Because the new chamber appears to predate the façade, its pottery and sediment dates are the best current evidence for the Treasury's chronology, and analysis is continuing.
What else is at Petra: Ad Deir, the theatre and the Great Temple
Petra is far bigger than the Treasury, and its largest monument is Ad Deir, "the Monastery", reached by a long climb of rock-cut steps. Its façade is about 45 metres high and 50 metres wide, carved in the same way as the Khazneh, from the top down, with the rock above trimmed back as the work descended. Probably carved in the mid-1st century CE, it was not a monastery and does not appear to be a tomb; an inscription nearby mentions a religious association of "Obodat the god", and scholars connect the complex with the cult of the deified king Obodas I. The nickname comes from crosses incised inside during the Byzantine period, when the space may have served as a church or hermitage.
The theatre, cut into the hillside along the main valley, could seat roughly 8,500 people. The Great Temple, one of the largest freestanding buildings in the city, and the nearby Qasr al-Bint temple show that Petra was a working capital, not only a necropolis.
How did Petra's water system work?
Petra's water system worked by catching every drop of scarce rain and defending the city against the violent flash floods that the same rain produced. UNESCO describes a network of channels, tunnels and diversion dams combined with a vast system of cisterns and reservoirs that controlled and conserved seasonal rainfall. Stored water carried the city through drought and could be sold to passing caravans.
The best-preserved example of flood control is at the entrance to the Siq. Here the Nabataeans built a dam across the Wadi Musa and cut the Al-Mudhlim tunnel through the rock, about 88 metres long and 12.8 metres high, to send floodwater around the gorge instead of through it, toward reservoirs and cisterns, while channels in the Siq walls carried clean water into the city.
Petra was badly damaged by an earthquake in 363 CE that destroyed many buildings and crippled the water network, and once maintenance lapsed the defences failed. The modern dam at the Siq entrance, the Bab as-Siq dam, was built in 1964 over the line of the original Nabataean one after a catastrophic flood: the Nabataean solution is still the one in use.
What happened to Petra?
Petra lost its independence when the Roman emperor Trajan annexed the Nabataean kingdom in 106 CE and made it part of the new province of Arabia Petraea (a few sources give 105). The city stayed occupied and built new monuments under Rome, but its economic base weakened as sea routes through the Red Sea carried more of the incense and spice trade and as rival caravan cities such as Palmyra drew Arabian commerce away.
The 363 CE earthquake was a further blow, and Petra slowly shrank over the following centuries. By the later Middle Ages it was known mainly to the local Bedouin, who continued to live in and around it.
How was Petra rediscovered?
Petra was reintroduced to Europe by the Swiss traveller Johann Ludwig Burckhardt, who reached it on 22 August 1812. Burckhardt was travelling in disguise as a Muslim scholar under the name Sheikh Ibrahim ibn Abdallah, and he persuaded a local guide to take him into the valley on the pretext that he wished to sacrifice a goat at the tomb of Aaron, Moses's brother, on the mountain above Petra. His visit was brief, but his account identified the ruins as ancient Petra. He died of dysentery in Cairo on 15 October 1817, aged 32, before he could make his planned crossing of the Sahara.
"Rediscovered" is a European framing, since local Bedouin never lost it. Petra became a UNESCO World Heritage Site in 1985, reached a global film audience in 1989 when the Treasury's façade stood in for the resting place of the Grail in Indiana Jones and the Last Crusade, and was named one of the New 7 Wonders of the World in 2007.
Is there still more to find at Petra?
Yes, and the 2016 satellite discovery shows how much can hide in plain sight. Archaeologists Sarah Parcak and Christopher Tuttle used high-resolution satellite imagery, followed by drone photography and ground survey, to identify a large monumental platform roughly 800 metres south of the city centre, about 56 by 49 metres, enclosing a smaller paved platform. Their results were published in the Bulletin of the American Schools of Oriental Research. Pottery from the surface pointed to construction beginning around the mid-2nd century BCE, which would make it one of the city's earliest public monuments.
The platform had never been systematically studied despite two centuries of research at Petra. With the 2024 tomb, it shows that remote sensing and radar are still changing Petra's story.
Billy Carson's reading
There is no Billy Carson video or book devoted specifically to Petra, so this article does not attribute a Petra-specific claim to him. His wider reading of rock-cut and megalithic sites is laid out in companion pieces. In the case of Baalbek and its Trilithon, Carson argues that the scale of the stones goes beyond what he accepts Roman-era logistics could achieve and points to an older foundation. In the case of Derinkuyu's underground city, he reads underground refuges on several continents as evidence of ancient populations responding to cataclysm. The common thread in his work is that ancient builders knew more than textbooks usually credit.
Petra is an instructive contrast case for that argument. Here the evidence for who built the monuments is unusually direct: Nabataean chisel marks on the façades, inscriptions in Nabataean Aramaic, tombs dated by pottery and sediment, and a water network whose design can still be traced on the ground. For readers who share Carson's view that ancient engineering is underestimated, Petra's hydraulics support the "more advanced than assumed" part, while showing that a documented people achieved it. His Megalithic Mysteries series invites exactly that kind of comparison with sites where the evidence is thinner.
Watch, read and go deeper
Billy Carson's Megalithic Mysteries on 4BK TV explores the stone sites at the centre of the ancient-engineering debate. For other cities carved or stacked out of rock, read the companion explainers on Machu Picchu and Nan Madol. To place the Nabataeans on the wider timeline of early cultures, see the ancient civilizations timeline, and for Billy's reading of humanity's earliest history, start with the Anunnaki topic hub.
Frequently asked questions
Who built Petra in Jordan?
Petra was built by the Nabataeans, an Arab trading people who settled the site from the 4th century BCE and made it their capital by the 2nd century BCE. Its most famous monuments, including the Treasury, date to the 1st century CE, when the kingdom was at its height under Aretas IV.
Is there really treasure in the Treasury at Petra?
No. Al-Khazneh was a royal tomb, and the name comes from a Bedouin legend that its stone urn held treasure. The urn is solid rock and carries bullet marks from people who tried to shoot it open. What the 2024 excavation found beneath the forecourt was a tomb containing 12 skeletons and grave goods, not gold.
How old is the Treasury at Petra?
Current scholarship dates Al-Khazneh to the early 1st century CE, most likely the first quarter of the century, during the reign of Aretas IV. A tomb found beneath it in 2024, dated by pottery and sediment analysis, supports that chronology.
How did the Nabataeans get water in the desert?
They built dams, channels, rock-cut tunnels, pipes, cisterns and reservoirs to capture seasonal rain and store it for dry periods. The same system diverted dangerous flash floods, most visibly through the 88-metre Al-Mudhlim tunnel at the Siq entrance. The network declined after an earthquake in 363 CE damaged it.
When was Petra rediscovered?
Swiss traveller Johann Ludwig Burckhardt reached Petra on 22 August 1812, disguised as Sheikh Ibrahim ibn Abdallah, and his account introduced it to European scholarship. Local Bedouin had lived there throughout.
Sources and further reading
- Diodorus Siculus, Library of History, book 19, on the Nabataeans and the campaign of Athenaeus in 312/311 BCE.
- UNESCO World Heritage Centre, "Petra", inscription and statement of outstanding universal value (1985).
- Johann Ludwig Burckhardt, Travels in Syria and the Holy Land (published posthumously, 1822).
- Sarah Parcak and Christopher Tuttle, "Hiding in Plain Sight: The Discovery of a New Monumental Structure at Petra, Jordan, Using WorldView-1 and WorldView-2 Satellite Imagery", Bulletin of the American Schools of Oriental Research 375 (2016).
- University of St Andrews news release on the tomb beneath Al-Khazneh, 15 October 2024.
- Jane Taylor, Petra and the Lost Kingdom of the Nabataeans (I.B. Tauris, 2001).
