The Desert Castles are located in the eastern desert of the Kingdom, which offer the fresco art and zodiac dome of Qasr Amra baths; fortress-like enigmatic Qasr Kharana; the Roman fort turned Umayyad residential palace at Qasr el Hallabat; and the black basalt Roman/Medieval Islamic fort at Azraq.

Qasr Kharaneh is the most impressive of the Desert Castles, and one of the best-preserved Umayyad monuments in Jordan

Consisting of around 60 rooms , arranged into two levels surrounded by a porticoes central courtyard.  A 3-quarter round buttress supports each of the four corners of the castle, and two quarter-round towers line the entrance in the middle of the south side, whereas half-round buttresses occupy the middle of the 3 remaining sides.

The inscription in a second-story room dates build Qasr Kharaneh to 711 CE, despite visible Sassanid influences.

The presence of Greek inscriptions around the main entrance frame suggests that the castle was built on the site of a Roman or Byzantine building.

The Castle remains an enigma to archaeologists and historians. Te function and use of the castle is not determined, it has been suggested that it was a defensive fort, while others argue it was a caravanserais for passing camel trains. However another theory is that it served as a retreat for Umayyad leaders to discuss affairs of state.

Qasr Amra is the best-known of the Desert Castles. Built as a Bath-House, early in the 8th century by the Umayyad Caliph and considered one of the most important examples of early Islamic Art, and Architecture 

The bath-house, the private retreat of the caliphs, was decorated with frescoes of luxurious flowers and fruit, naked musicians, hunting scenes and some of the scenes of their conquest of neighboring lands.

Its' entrance leads directly into the main hall which is divided into three aisles.

The ceiling of the main aisle is covered with frescoes showing everyday people at work, a carpenter, a metalworker, a baker, etc. The dome of the baths, probably the steam room is decorated with a map of the northern hemisphere sky, accompanied by signs of the zodiac.

The frescoes are badly faded and tarnished with age, and many are defaced by graffiti

It is on the list of UNESCO's World Heritage sites.

Azraq Palace was originally built as a Roman fortress and restored by the Caliphs in 1237 as a Mosque.  However, the mosque was built in the courtyard, placed crossways because of the necessity of facing Mecca.  Leading off the courtyard are doors to the dining hall and to the kitchens.  There are also stables for horses.

A legacy of the Romans is the great basalt doors, still swinging on their hinges. The main door is one solid slab of stone, and the west tower also has one of these massive portals.

Qasr Hallabat is probably the most ruinous of the Desert Castles. Originally a Roman fort was built on this small hill using the stones of black basalt.

It was restored by the Omayyads in the eighth century and some beautiful mosaics were laid down, some fragments of which are still to be seen in the rooms off the courtyard.

It was another pleasure palace.