Petra
Petra is a historic 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.
The site remained unknown to the Western world until 1812, when it was introduced by Swiss explorer Johann Ludwig Burckhardt. It was described as "a rose-red city half as old as time" in a Newdigate Prize-winning sonnet by John William Burgon. UNESCO has described it as "one of the most precious cultural properties of man's cultural heritage.” Petra was chosen by the BBC as one of "the 40 places you have to see before you die.
Excavations have demonstrated that it was the ability of the Nabataeans to control the water supply that led to the rise of the desert city, creating an artificial oasis. The area is visited by flash floods and archaeological evidence demonstrates the Nabataeans controlled these floods by the use of dams, cisterns and water conduits. These innovations stored water for prolonged periods of drought, and enabled the city to prosper from its sale
Although in ancient times Petra might have been approached from the south via Saudi Arabia on a track leading around Jabal Haroun ("Aaron's Mountain"), across the plain of Petra, or possibly from the high plateau to the north, most modern visitors approach the site from the east. The impressive eastern entrance leads steeply down through a dark, narrow gorge (in places only 3–4 m (9.8–13 ft) wide) called the Sig ("the shaft"), a natural geological feature formed from a deep split in the sandstone rocks and serving as a waterway flowing into Wadi Musa. At the end of the narrow gorge stands Petra's most elaborate ruin, Al Khazneh (popularly known as "the Treasury"), hewn into the sandstone cliff.