By the late 9th and early 10th centuries, Baghdad's unequaled brilliance, which had flourished under the Abbasids for generations, began to face the pressures of scale, complexity, and external pitfalls. The megacity, which had formerly been a strictly organized center of administration, commerce, and intellectual bid, now plodded to attune its sprawling population, different communities, and the demands of an conglomerate that extended from the Mediterranean to Central Asia. The Round City, with its concentric walls, wide conduits, and monumental palaces, remained magnific, but beneath its beauty, subtle strains were