Theories as to the qasr's purpose include a Crusader's castle, a military stronghold, agricultural outpost, and resting place for caravan travelers.

[3] On the inside, the building has 60 rooms on two levels arranged around a central courtyard, with a rainwater pool in the middle.

[3] The palace is located along the Al-Azraq Highway in a remote area of the Jordanian desert, isolated from human settlement.

Thamail are pits dug into the gravel that rests upon the bedrock in the wadi, where they collect water.

In 1895, Sir John Edward Gray Hill, an English explorer, noted two deep cisterns that had apparently fallen out of use.

[5] Unfortunately, he didn't expand on this observation, and no one else has recorded the existence of any water storage apparatus, like dams or irrigation lines, besides thamail in the wadi bed.

The small scale of water production and storage means it is unlikely that anyone depended on the building to support large groups, especially for long periods of time.

This discounts the theories that the qasr was used as a caravanserai (a resting place for traders), an agricultural outpost, or a palace intended for recreation.

[2] Qasr Kharana is located far from both of these routes, so it is unlikely that it was intended as a service point for caravan traders, since it is not only remote, but had little water to offer.

While it lacked the infrastructure to support long-term stays of large groups, it has stables, plenty of rooms, and a courtyard which would have been conducive to meetings.

[2] Qasr Kharana combines different regional traditions with the influence of the then-new religion of Islam to create a new style.

[7]Like Sassanid buildings, the castle's structural system is transverse arches supporting barrel vaults.

[6] Islamic concepts of public and private were satisfied through the narrow slits offering views to (and from) the outside, larger windows on the inside and the north terrace separating the two apartments.

Instead they served to control dust and light and took advantage of air pressure differentials to cool the rooms, via the Venturi effect.

[6] The architectural style and the decoration of the building show influences from Syrian, Parthian, and Sasanian traditions.

In a large room on the west side of the first floor, there is a small inscription which states it was written on November 24, 710 CE.

He gave a fairly accurate description of the palace, although he misread his compass and said the south entrance was on the east facade.

This led to his conclusion that the building was a Crusader’s castle, “intended to be used as a stronghold and water store between Umm Moghr and Asrak”.

In an effort to justify this, he included battlements in his schematic drawings and baselessly claimed that they had been torn down so that their stones could be reused as weapons.

[2] In 1922, Antonin Jaussen and Raphaël Savignac published a description of Qasr Harrana in their Mission archéologique En Arabie,[10] which has been praised as a "scholarly landmark".

[11] In 1946, Nabia Abbott published a full translation and analysis of the inscriptions at Qasr Harrana.

[6] Stephen Urice wrote his doctoral dissertation on the castle, published as a book, Qasr Kharana in the Transjordan, in 1987 following the restoration.

A paved driveway leads from the highway to a parking lot large enough for cars and several buses located just south of the entrance.