The Great Mosque is located in the northern section of the city's heart. Its plan is rectangle (108m x 92m) with 1.7m thick mud brick walls fortified with semi-circular towers at the corners. All that remains today are the baked brick minaret and prayer hall (haram) façade with eleven arches that were added by Nur al-Din al-Zanki during the 1165 renovation of the mosque.
The remaining traces of the haram columns indicate that the space was divided into three riwaqs parallel to the qibla. These riwaqs were covered with pitched roofs similar to the Umayyad mosque in Damascus. The architecture of the mosque is a blend of both Syrian and Mesopotamian styles that influenced this site with its central location between Damascus and Baghdad.
Source:
Rihawi, Abdul Qader. 1979. Arabic Islamic Architecture: Its Characteristics and Traces in Syria. Damascus: Publications of the Ministry of Culture and National Leadership. 90-91.