>>6044312
https://en.wikipedia.org/wiki/Round_city_of_Baghdad
The old Baghdad was a small village, and despite its name, which is of Iranian origin (bag "god" + dād "gifted"), the original inhabitants were probably Aramaic-speaking Nabateans. The new city, however, was mainly Arabic-speaking, with considerable Persian elements in the population and urban environment, although there have not been any major Persian settlement in the village of Baghdad or its surrounding communities, all of which were absorbed into the new city of Baghdad. The Persian elements rather appeared after the foundation of the new city, and included Persian architectural influence, Persian military settlement in the early years, the continuing settlement of Persian scholars, and the late rulers of Persian origin (such as the Buyids).[5]
The city was designed as a circle about 1 km (0.62 mi) in diameter, leading it to be known as the "Round City". The original design shows a ring of residential and commercial structures along the inside of the city walls, but the final construction added another ring, inside the first.[6] In the center of the city lay the mosque, as well as headquarters for guards. The purpose or use of the remaining space in the center is unknown. The circular design of the city was a direct reflection of the traditional Persian Sasanian urban design. The ancient Sasanian city of Gur/Firouzabad is nearly identical in its general circular design, radiating avenues, and the government buildings and temples at the center of the city. This points to the fact that it was based on Persian precedents.[7][8] The two designers who were hired by al-Mansur to plan the city's design were Naubakht, a former Zoroastrian,[9] and Mashallah ibn Athari, a Muslim astrologer/astronomer.
The city had four gates: Bab al-Kufa ("gate of Kufa"), Bab al-Sham ("gate of al-Sham or Damascus"), Bab al-Khorasan ("gate of Khorasan"), and Bab al-Basra ("gate of Basra").[10] This too is similar to the round cities of Darabgard and Gor, which had four gates.[8] The Khuld Palace, the main palace of Baghdad built by al-Mansur, was located near the Bab al-Khorasan.[11] The Khorasan Gate marked the beginning of the Great Khorasan Road.