The first nucleus of the city of Baghdad was the “Round City” (Madinat al-Salam) founded by the Abbasid caliph al- Mansur in 762 AD and completed in 766 AD on the west bank of the Tigris in a strategic location in the middle of Mesopotamia. The original plan, of almost 1km in diameter, followed a defensive scheme with four axial gates while the caliph’s domed residence and a congregational mosque were located at the centre together with two other administrative buildings, the “police” and the commander of the guards.
Streets would lead from the four gates to the central areas while the living quarters and commerces were concentrated in a ring between the exterior wall of the city which was surrounded by a deep moat and a second fortified round wall. The four gates would each one point towards a different city — Basra, Kufa, Khurasan and Damascus — and named after that. The Kufah Gate was on the major road which connected the city to Mecca while the Anbar gate reached the bridges over the Euphrates River to the city.
The gates would open onto an arcaded street running all around the exterior inhabited ring, the four streets coming from the gates would divide the city into four districts all crossed by the arched road.
Many hypotheses have been formulated to explain the choice of the circle as the geometrical form of the city, most of them relate the urban scheme with symbolical levels connected to the Islamic culture.
At first, the city was designed as an administrative centre and later became a dynamic urban centre with markets and growing residential areas.
In a further moment, a second settlement known as Mu’asker al-Mahdi was founded on the east bank of the Tigris.
Ana Maria Negoitã’s “The City Of Mansur The Builder. Baghdad Between The Caliph’s Will AndShari’ah Norms“