jordan - petra:

Petra was first established sometime around the 6th century BC, by the Nabataean Arabs, a nomadic tribe who settled in the area and laid the foundations of a commercial empire that extended into Syria. Despite successive attempts by the Seleucid king Antigonus, the Roman emperor Pompey and Herod the Great to bring Petra under the control of their respective empires, Petra remained largely in Nabataean hands until around 100AD, when the Romans took over. It was still inhabited during the Byzantine period, when the former Roman empire moved its focus east to Constantinople, but declined in importance thereafter. The Crusaders constructed a fort there in the 12th century, but soon withdrew, leaving Petra to the local people until the early 19th century, when it was visited by the Swiss explorer Johann Ludwig Burckhardt.

Petra lies about 3-5 hours south of modern Amman, about 2 hours north of Aqaba, on the edges of the mountainous desert of the Wadi Araba. The city is surrounded by towering hills of rust-coloured sandstone which gave the city some natural protection against invaders.
 

The site is semi-arid, the friable sandstone which allowed the Nabataeans to carve their temples and tombs into the rock crumbling easily to sand. The colour of the rock ranges from pale yellow or white through rich reds to the darker brown of more resistant rocks. The contorted strata of different-coloured rock form whorls and waves of colour in the rock face, which the Nabataeans exploited in their architecture.