Located in an oasis at 500 m of altitude, and 130 km at the East of Amman. It extends on the edge of a basaltic lava flow, a calcareous zone, and a small alluvial basin charged with salts. A true natural reserve which occupies 100 km2.

The castle was mostly built from blocks of basalt by the Romans to defend this important water point and to control one of the invasion ways of Syria by the tributes of the desert. It was also the headquarters of Lawrence of Arabia and king Feysal.