On 30 July 762, after the royal astrologers had declared this the most auspicious date for building work to begin, Mansur offered up a prayer to Allah, laid the ceremonial first brick and ordered the assembled workers to get cracking. The scale of this great urban project is one of the most distinctive aspects of the story of Baghdad. With a circumference of four miles, the massive brick walls rising up from the banks of the Tigris were the defining signature of Mansur’s Round City.
