Petra

Petra, is an archaeological site in the Arabah, Ma'an Governorate, Jordan, lying 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. It is renowned for its rock-cut architecture. Petra is also one of the new wonders of the world. The Nabateans constructed it as their capital city around 100 BCE.

The site remained unknown ... more on en.wikipedia.org