Discovered via Archaeology & Art — Twitter is actually good for something if you use it right — with this amazing photo.
They carved it out of a mountain.
2100 years ago — at least — by hand.
The Nabataeans were nomadic Arabs who not only carved amazing buildings and art from solid rock, but created a luscious green oasis in a desert by mastering rainwater retention.
They specifically chose this location because it was a natural fortress with only small openings through the mountainous desert terrain, and because it was on an incense trade route.
And so it became a prosperous city, carved out of the mountains.
They carved this out of a mountain too.