Early Islamic Fortifications; Ukmaydir, (Section through the gate), Umayyad, Iraq

Early Islamic Fortifications, B+Qasr Hallabat, Umayyad, Jordan

Baghdad; Round City and section through gate - Abbasid, Iraq

Baghdad, of course remains the most famous memorial to the Abbasids, 

although nothing remains of the fortified Round City built for the Caliph

 Mansur (754 - 775).  Its purpose was to serve as an administrative capital, 

a Caliphal palace, and a place to settle thousands of Khurasani-Arab troops.  

The location of Baghdad was also particularly good for communications.  

Militarily it housed a large army at the center of the state; these forces 

included regular troops, the Caliph's own guard, the city's shurta police 

and haras internal security force, as well as Baghdad's own paramilitary 

militia.  The great majority of the population, which may have reached 

as many as a half-million by the year 800, lived in sprawlingsuburbs 

around the Round City, some of which had been built by Khurasani 

military chiefs to house their own followers.

Reference:

D. Niccole and Angus McBride(illus.), "Armies of the Muslim Conquest," Men-At-Arms 225, Osprey Pub., 1993, Pages 23-24.

Respectfully Submitted;

Marcus Audens

Atshan, Umayyad, Iraq

Qasr al Hayr, al Ghure, Umayyad, Iraq

Qasr Hallabat, Umayyad, Jordan

Harunlye, Abbasid, Turkey

The Gate diagram of Ukhaydir, Umayyad, Iraq

Qala'at Rustaq, Early Islamic Oman

The 'later tower' means that sometime since the fortification was 

constructed, a tower was added  to the curtain wall.  It was

 well known that as european forces came into contact with 

muslim forces at a fortification, the Muslim engineers, borrowed 

the technology that they saw in the improvements of their 

opponent's fortifications . 

Muslim State at the Death of Muhammad in 632 CE

Reference:

D. Nicolle, et al, "Armies of the Muslim Conquest," Men-At-Arms 225, Osprey, 1993, P. 4