July 30, 762 - Baghdad is founded.
After their victory over the Umayyads, the Abbasids - the new ruling dynasty in the Arab Empire - wanted a new capital from which to rule. On July 30, 762, Caliph Al-Mansur therefore ordered the founding of a new city on the banks of the Tigris, north of the ancient cities of Ctesiphon and Babylon. He baptised it "Madinat al-Salaam", City of Peace. However, the people continued to use the name of the pre-existing settlement: "Baghdad".
The location of the new city was strategically chosen. On the one hand, the city was on the dominant trade routes along the Tigris River. On the other hand, in both the north and the south of the city, there is water nearby - Baghdad is located near a meander of the Tigris - so that all households could be sufficiently supplied.
The markets of Baghdad attracted a large number of people from far and wide. They brought new prosperity, knowledge and literature. In the ninth century, this would make Baghdad a true world center of science and philosophy. The Islamic golden age had arrived.
Bonus fact: the city center was designed as a perfect circle, following the traditional Sassanid city planning. Unfortunately, nothing of this city center remains today. We only know this from surviving writings.