Founding of Baghdad (762): al-Mansur's Round City on the Tigris

The founding of Baghdad in 762 created the capital of the Abbasid caliphate and one of the great cities of the medieval world. On the west bank of the Tigris in central Iraq, the caliph al-Mansur built a fortified circular city, officially called Madinat al-Salam, the City of Peace. Within a few generations it had grown far beyond its walls into a centre of trade, government and learning that dominated the Islamic world.

Background: a dynasty in search of a capital

The Abbasids came to power in 750, when a revolution that began in Khurasan in eastern Iran overthrew the Umayyad caliphate based in Damascus. The new rulers did not want to govern from Syria, the heartland of their defeated rivals. Their support lay in Iraq and in the east, among Arabs settled in Khurasan and among Persian converts.

The first Abbasid caliph, Abu al-Abbas al-Saffah, and his brother and successor Abu Jafar al-Mansur (r. 754–775) used several temporary residences near Kufa, each called al-Hashimiya. These proved unsatisfactory. Kufa was a restless city with its own political loyalties, and in 762 a rising in support of a rival branch of the Prophet’s family, led by Muhammad al-Nafs al-Zakiyya, showed how exposed the dynasty still was.

Al-Mansur decided to build a new capital from scratch, one that would be safe, easy to supply and clearly the seat of the Abbasid caliphate alone.

Choosing the site

Medieval historians, especially al-Tabari and al-Yaqubi, say that al-Mansur personally surveyed the land along the Tigris. He chose a spot near a small settlement called Baghdad, a few kilometres north of the ruined Sasanian capital Ctesiphon.

The location had clear advantages. Here the Tigris and the Euphrates come closest together, and canals linked the two rivers, so goods could arrive by water from northern Mesopotamia, from the Gulf and from Syria. The surrounding farmland was rich, and the main roads to Iran and Khurasan crossed the area. Medieval writers record al-Mansur praising the site as a place where ships could bring the produce of the whole world to his door; such speeches are literary reconstructions, but the logic of trade and supply is clear.

According to tradition, the court astrologers Nawbakht and Mashallah ibn Athari chose an auspicious moment for laying the foundations. The date usually given is 30 July 762.

Building the Round City

The new city was laid out as a near-perfect circle. Reconstructions of its diameter range from about 2 to 2.7 kilometres. Medieval sources say that tens of thousands of builders, craftsmen and labourers were gathered from across the empire; a figure of 100,000 workers appears in the chronicles, but it should be treated as a rough indication rather than a count. Construction used sun-dried and fired brick, and some materials were reportedly taken from older sites nearby.

The defences were formidable:

• A moat fed by canal water ran around the outside.
• Two concentric walls of mud brick, the inner one much higher and thicker, enclosed the city.
• Four gates stood at equal intervals, named after the regions their roads led to: the Kufa Gate (south-west), the Basra Gate (south-east), the Khurasan Gate (north-east) and the Syria Gate (north-west).

Each gateway passed through a bent entrance and a series of courts, so that attackers could not ride straight in. Above each gate was a domed audience chamber from which the caliph could view the surrounding country.

Inside the walls

Between the walls ran a ring of houses and markets for officials, guards and the caliph’s household, divided by streets radiating from the gates. The core of the circle was a vast open space. At its centre stood the caliph’s palace, known as the Golden Gate, crowned by a green dome that was said to be visible from far away, with the great mosque built against it.

The layout had a clear meaning. The ruler sat at the exact centre of his city and, symbolically, of his empire, with every road leading to him. Circular cities were not new in the region: Parthian and Sasanian towns such as Hatra and Ardashir-Khurrah (Firuzabad) in Iran had used round plans. Al-Mansur adapted an old idea on an imperial scale.

The Round City was largely complete by about 766, and the government moved in. It was always more of a palace-city than an ordinary town, housing the court, the treasury, the administration and the army command.

Growth beyond the walls

The circle soon became too small. In about 773 al-Mansur moved the markets out of the Round City to the suburb of al-Karkh to the south, reportedly for security reasons after a visiting Byzantine envoy remarked on the danger of letting strangers into the heart of the capital. Whatever the exact motive, commerce now flourished outside the walls.

Soon after, al-Mansur built a new palace, al-Khuld, on the Tigris just outside the circle. On the east bank he began a military settlement, al-Rusafa, for his son and heir al-Mahdi. Bridges of boats linked the two banks. By the reign of Harun al-Rashid (786–809), Baghdad was a sprawling metropolis of palaces, mosques, markets, canals and residential districts.

Estimates of its population in the 9th and 10th centuries vary widely, commonly from several hundred thousand to around a million. Whatever the true figure, it was among the largest cities in the world at the time, comparable to Constantinople and the Chinese capital Chang’an.

A centre of the world

Baghdad’s wealth drew merchants, scholars and craftsmen from across Asia, Africa and Europe. Paper, introduced from Central Asia, became a local industry in the late 8th century. Under the caliph al-Ma’mun (r. 813–833) the city became the centre of a major translation movement associated with the House of Wisdom, in which Greek, Persian and Indian works were rendered into Arabic.

The Round City itself declined. During the civil war between al-Amin and al-Ma’mun in 811–813, Baghdad was besieged and badly damaged. From 836 to 892 the caliphs moved their residence to Samarra, further up the Tigris. When they returned, they built new palaces on the east bank, and the old circle was gradually absorbed into the surrounding urban fabric. No visible trace of it survives today.

Key people

• Abu Jafar al-Mansur (c. 714–775): second Abbasid caliph, founder of Baghdad and the real architect of the Abbasid state.
• Muhammad al-Mahdi (r. 775–785): al-Mansur’s son, for whom the east-bank district of al-Rusafa was built.
• Nawbakht and Mashallah ibn Athari: astrologers traditionally credited with choosing the foundation date.
• Al-Yaqubi (d. after 905) and al-Tabari (d. 923): historians whose accounts are the main sources for the city’s founding.

Timeline

• 750: The Abbasid revolution overthrows the Umayyad caliphate.
• 754: Al-Mansur becomes caliph.
• 762, July: Foundations of the Round City are laid on the Tigris, traditionally on 30 July.
• c. 766: The Round City is largely complete and becomes the seat of government.
• c. 773: Markets are moved out to al-Karkh; the al-Khuld palace is built.
• 775: Death of al-Mansur; al-Mahdi succeeds him.
• 812–813: Baghdad is besieged during the civil war between al-Amin and al-Ma’mun.
• 836: The caliph al-Mu’tasim moves the court to Samarra.
• 892: The caliphs return to Baghdad.

Why it matters

The founding of Baghdad marked the shift of the Islamic world’s centre of gravity from Syria to Iraq and towards Iran. For five centuries, until the Mongol siege of Baghdad in 1258, the city was the symbolic seat of the caliphate. Its planned origins, cosmopolitan population and role in science and literature made it a byword for the wealth and culture of the medieval Islamic world.