The workforce itself was of a stupendous size. Thousands of architects and engineers, legal experts, surveyors and carpenters, blacksmiths, diggers and ordinary labourers were recruited from across the Abbasid empire. First they surveyed, measured and excavated the foundations. Then, using the sun-baked and kiln-fired bricks that had always been the main building material on the river-flooded Mesopotamian plains in the absence of stone quarries, they raised the fortress-like city walls brick by brick. This was by far the greatest construction project in the Islamic world: Yaqubi reckoned there were 100,000 workers involved.
The circular design was breathtakingly innovative. “They say that no other round city is known in all the regions of the world,” Khatib noted approvingly. Four equidistant gates pierced the outer walls where straight roads led to the centre of the city. The Kufa Gate to the south-west and the Basra Gate to the south-east both opened on to the Sarat canal – a key part of the network of waterways that drained the waters of the Euphrates into the Tigris and made this site so attractive. The Sham (Syrian) Gate to the north-west led to the main road on to Anbar, and across the desert wastes to Syria. To the north-east the Khorasan Gate lay close to the Tigris, leading to the bridge of boats across it.
