Ad Deir ("The Monastery"; Arabic: الدير ), also known as El Deir, is a monumental building carved out of rock in the ancient Jordanian city of Petra. Built by the Nabataeans in the 1st century and measuring 50 meters wide by approximately 45 meters high, architecturally the Monastery is an example of the Nabatean Classical style. It is the second most visited building in Petra after Al Khazneh.
Petra (Arabic: البترا, Al-Batrāʾ; Ancient Greek: Πέτρα), originally known as Raqmu to the Nabataeans, is a historical and archaeological city in the southern Jordanian governorate of Ma'an that is famous for its rock-cut architecture and water conduit system. Another name for Petra is the Rose City due to the color of the stone out of which it is carved. Established possibly as early as 312 BC as the capital city of the Arab Nabataeans, it is a symbol of Jordan, as well as Jordan's most-visited tourist attraction. It lies on the slope of Jebel al-Madhbah (identified by some as the biblical Mount Horin 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 poem by John William Burgon. UNESCO has described it as "one of the most precious cultural properties of man's cultural heritage".Petra was named amongst the 7 New Wonders of the World in 2007 and was also chosen by the Smithsonian Magazine as one of the "28 Places to See Before You Die".