Petra is a historical and archaeological city in the Jordanian governorate of Ma'an that is known for its rock cut architecture and water conduits system. Established sometime around the 6th century BC as the capital city of the Nabataeans, it is a symbol of Jordan as well as its most visited tourism attraction. It lies on the slope of Mount Hor in a basin among the mountains which form the eastern flank of Arabah (Wadi Araba), the large valley running from the Dead Sea to the Gulf of Aqaba. Petra has been a UNESCO World Heritage Site since 1985.

Satisfactory evidence of the date of the earliest Nabataean settlement may be obtained from an examination of the tombs. Two types have been distinguished: the Nabataean and the Greco-Roman. The Nabataean type starts from the simple pylon-tomb with a door set in a tower crowned by a parapet ornament, in imitation of the front of a dwelling- house. Then, after passing through various stages, the full Nabataean type is reached, retaining all the native features and at the same time exhibiting characteristics which are partly Egyptian and partly Greek. Of this type there exist close parallels in the tomb-towers in north Arabia, which bear long Nabataean inscriptions and supply a date for the corresponding monuments at Petra. Then comes a series of tombfronts which terminate in a semicircular arch, a feature derived from north Syria. Finally come the elaborate façades copied from the front of a Roman temple; however, all traces of native style have vanished. The exact dates of the stages in this development cannot be fixed. Strangely, few inscriptions of any length have been found at Petra, perhaps because they have perished with the stucco or cement which was used upon many of the buildings. The simple pylon-tombs which belong to the pre-Hellenic age serve as evidence for the earliest period. It is not known how far back in this stage the Nabataean settlement goes, but it does not go back farther than the 6th century BCE.

Petra declined rapidly under Roman rule, in large part from the revision of sea-based trade routes. In 363 an earthquake destroyed many buildings, and crippled the vital water management system. The ruins of Petra were an object of curiosity in the Middle Ages and were visited by Sultan Baibars of Egypt towards the end of the 13th century. The first European to describe them was Johann Ludwig Burckhardt in Because the structures weakened with age, many of the tombs became vulnerable to thieves, and many treasures were stolen.

The site suffers from a host of threats, including collapse of ancient structures, erosion due to flooding and improper rainwater drainage, weathering from salt upwelling, improper restoration of ancient structures, and unsustainable tourism. The latter has increased substantially ever since the site received widespread media coverage in 2007 during the controversial New Seven Wonders of the World Internet and cell phone campaign, started by a private corporation.

On December 6, 1985, Petra was designated a World Heritage Site. The site is featured in films such as: Indiana Jones and the Last Crusade, Arabian Nights, Passion in the Desert, Mortal Kombat: Annihilation, Sinbad and the Eye of the Tiger, the Sisters of Mercy music video "Dominion", and Transformers: Revenge of the Fallen. It was recreated for the video games Spy Hunter (2001), King's Quest V, Lego Indiana Jones and Sonic Unleashed and appeared in the novels Left Behind, Appointment with Death, The Eagle in the Sand and The Red Sea Sharks, the nineteenth book in The Adventures of Tintin series. It featured prominently in the Marcus Didius Falco mystery novel Last Act in Palmyra. In Blue Balliett's novel, Chasing Vermeer, the character Petra Andalee comes from the site.

Petra was the main topic in John William Burgon's Poem Petra. Referring to it as the inaccessible city which he had heard described but had never seen. The Poem was awarded the Newdigate Prize in 1845 : It seems no work of Man's creative hand, by labour wrought as wavering fancy planned; But from the rock as if by magic grown, eternal, silent, beautiful, alone! Not virgin-white like that old Doric shrine, where erst Athena held her rites divine; Not saintly-grey, like many a minster fane, that crowns the hill and consecrates the plain; But rose-red as if the blush of dawn, that first beheld them were not yet withdrawn; The hues of youth upon a brow of woe, which Man deemed old two thousand years ago, match me such marvel save in Eastern clime, a rose-red city half as old as time.