A gate connects these two buildings through a passageway, which is centrally positioned on the wall that they share; their floor plans are identical. Each flanked by two very small, protruding square rooms, two main entrances are located at the center of each enclosure's northern façade. A total of fourteen semicircular towers at equal intervals buttress the structure's stone exterior, including four at the outer corners and two at the joining corners of the buildings. Upon entering, a long hallway opens into a courtyard surrounded by suites of rooms (bayts). In decoration, design, and material, Qasr al-Tuba is reminiscent of Qasr al-Mshatta; it is speculated that they were built at the same time. Both palaces feature masonry exteriors with brick interior work, with the construction of some doorways replicating each other perfectly and both including pointed brick vaults. In addition, latrines are found in towers at both sites and the decoration on the doorposts and lintels at Qasr al-Tuba mimic Mshatta. Neither were completed. 

Sources: 

Creswell, K. A. C. A Short Account of Early Muslim Architecture. Edited by James W. Allan. Aldershot: Scolar Press, 1989. 

Rashdān, Wā'il Munīr. al-Qusūr al-Umawī fī al-Mamlaka al-Urduniyya al-Hāshimiyya: dirāsa mi'mariyya, 87-90. Riyadh: Jāmi' al-Malik Sa'ūd, 1430 [2009].