A.D. 762 the Abbasid Caliph al-Mansur began construction of a new administrative center at a place where the Tigris and Euphrates Rivers flow close to each other and were joined by a canal. Al-Mansur named his new capital Madinat al-Salam, meaning City of Peace, but the name by which we know the city, Baghdad, comes from earlier settlements at the site and may date from as long ago as the time of Hammurapi, about 1800 B.C.
Detailed accounts written at the time of construction and in the years following when Baghdad was the cultural center of the Islamic world relate that al-Mansur built the core of his city as an enormous fortified circle almost a mile and half in diameter. The circle was cut by four equally spaced gates, and from each gate a broad, paved road arrowed toward the center, piercing a series of walls before reaching the palace in a central square. A traveler arriving at Baghdadperhaps for an audience with the caliphwould first cross a moat some 65 feet (20 meters) wide and then go through an outer wall, reported to have been 30 feet (10 meters) thick. Inside that wall, the traveler crossed a wide ring of open ground surrounding a second wall. This wall, the main defense wall, was 150 feet (45 meters) thick at its base and 100 feet (30 meters) high. Inside the main wall, our traveler found another open ring, although in this space the avenue he traveled on was lined with arcades for shops and markets. From the primary roads, streets were carefully laid out for residential areas designed to include neighborhood mosques and baths. Continuing toward the center of the city, the traveler passed through a third wall and at last entered the inner circle of Baghdad. Here stood the caliph's palace, topped by a great green dome that rose to a height of 150 feet (45 meters) and was surmounted by a statue of a horseman. Flanking the palace were the caliph's mosque, houses for the royal family, and offices for important administrative departments.
Today nothing remains that can be identified as a part of al-Mansur's city. Almost as soon as it was completed the public markets were moved outside the circular walls for security purposes. Suburbs grew around the market and soon spread to both sides of the Tigris. Later caliphs built new palaces outside the walls and soon the old section fell into disrepair. After a disastrous flood in 1075, the caliph took down a portion of the original fortifications and then, over time, as the city grew and building materials were needed, the old city simply disappeared.—Patricia Kellogg