For much of its extraordinary life, Baghdad, known for centuries as the "City of Peace," enjoyed both cultural and commercial preeminence. For five centuries it was the seat of the Abbasid Empire, a marvel of glittering palaces, exquisite parks, magnificent mosques, and Islamic colleges. It was a city boasting the most accomplished astronomers, mathematicians, doctors, musicians, and poets-- it was here, in the time of the caliphs, that the great...