BAGHDAD—a city that changed from a geography to a word in a fable. This probably all began when the 9th-century Caliph al-Masur heard that the old Babylonian city of Baghdad was a place of cool afternoons in the summer. And so in 762 the Caliph moved his residence from Hashimiya, and brought all the government offices from Kufa. It took four years for the city to be built by 100,000 laborers and artisans. Gradually, palaces, buildings,