Like the "Treasury," the name "Monastery" is a rather inaccurate nickname, which is probably based on its remote location and some inscribed crosses in the interior. Althought it may have been later used as a church (or even a hermitage), it was probably a temple. It may have been dedicated to the deified Nabatean king Obodas I, who reigned in the 1st century BC.
The Monastery is similar to design to the Treasury, but it is much larger (50 m high x 45m wide) and much less decorated. The facade is flat on the lower level and deeply carved on the upper level, with engaged columns and two half-pediments flanking a central urn (10m high).
The flat plaza in front was carved out of the rock, perhaps to accommodate crowds at religious ceremonies. It was originally surrounded by a colonnade. The interior consists of a single room with double staircases leading up to a niche (the same layout as in the Qasr al-Bint and the Temple of the Winged Lions).
(Best viewed in Original size.)