One of the earliest mosques in Islam, the original Great Mosque at Kufa was built on a square site determined by lances thrown outwards in the four cardinal directions. It was constructed in the middle of the 7th century after the Caliph Omar established the city. Surrounded by a trench, it possessed an arcade of marble columns that extended 20 meters in length. It measured approximately 100 square meters with the side of the qibla organized into five aisles and the others arranged into two. According to early literary sources, the aisles were demarcated by masonry block columns that rose to the height of the mosque's flat roof, which is described as being rather high. Creswell posits that the design was reminiscent of an apadana, an architectural structure referring to a "Hall of Columns" for Persian kings.
The mosque has been redeveloped in various phases over the years and today it features an elegant gold dome and Saffavid tile work from the 17th and 18th centuries. Twenty-eight semi-circular towers support the exterior wall; it is speculated that they date to the early Islamic period. During excavation, the Iraqi Department of Antiquities learned that although these towers stretched two meters into the ground, they were being stabilized by another set of differently sized towers beneath them, that at one point belonged to an earlier mosque on the site. Furthermore, these excavations provided evidence that the qibla side of the mosque is structurally connected to the west wall of the Dar al-Imara. Please see the Dar al-Imara site for more information.
Sources:
Creswell, K. A. C.1989. A Short Account of Early Muslim Architecture. Rev. ed. Allan, James W. Aldershot: Scolar Press, 9-10.
Ettinghausen, Richard and Grabar, Oleg. 1987. The Art and Architecture of Islam 650-1250. New Haven and London: Yale University Press, 35-36.
Hillenbrand, Robert. 1994. Islamic Architecture. Edinburgh: Edinburgh University Press, 38.