Petra in jordan is on the BBC-list of the 20 places to see before you die. This narrow gorge was the only way in to a society of 50.000 people 700 bc - notice the waterchannel cut out in the left side of the mountain. It was well placed on the spice and silk-route to Asia. The Romans later conquered the city and was in charge untill an eartquake buried everything 700 ac.
Only about 10 percent of the original city-area has been investigated.