ABSTRACT
Although Baghdad is believed to have been built on the Tigris River as the seat of government for the Abbasid Dynasty in 762, a city of the same name is mentioned in pre-Islamic texts. It seems likely, then, that the Abbasid city was built on the site of an earlier town. Baghdad also sits just to the north of the site of the ancient city of Babylon. The original city was built on a circular layout, with two concentric walls surrounding a central mosque. By the late eighth century, Baghdad may well have been the largest city in the world as well as a major center of learning and trade.
