El-Deir Monastery, Petra. Built in the 3rd century BC. Similar in design to the Khazneh, the monastery is infact much larger and more eroded. El-Dier is called a monastery because it appears to have been used as that during the Byzantine Christian period.Petra was the ancient capital of the Nabateans - Arabs who dominated the Transjordan area in pre-Roman times. Petra means 'rock' in Greek. It has been called the 'rose-red city half as old as time' by Dean Burgen in his poem called 'Petra'. The Romans took the city in 106 AC and transformed it into a Roman city. By the time the Muslim invasion of the 7th century, Petra had fallen into obscurity. From then until the 19th century it was a forgotten city known only to local Bedouin inhabitants. In 1812, a young Swiss explorer and convert to Islam, Johann Ludwig Burckhardt managed to bluff his way through and report to the outside world that the ruins at Wadi Musa were those of the ancient city of Petra.