Founding of Baghdad in 762: The Round City, al-Mansur, Plan and Legacy

Baghdad was founded as an Abbasid imperial capital by caliph al-Mansur in 762. The original court foundation was called Madinat al-Salam, the City of Peace, and medieval descriptions present it as a great circular enclosure with four gates, radial streets, a central palace and a congregational mosque. That Round City was only the first administrative core. Markets, neighborhoods, military quarters and palaces soon expanded across both banks of the Tigris. Because no visible remains of al-Mansur's circle survive, every modern plan is a reconstruction from texts, not a photograph of an excavated city.

Quick facts about Baghdad's foundation

• Founder: Abu Jafar al-Mansur, the second Abbasid caliph.
• Foundation date: construction began in 145 AH / 762 CE and continued over the following years.
• Official court name: Madinat al-Salam, commonly translated as City of Peace.
• Form: a circular or rounded fortified administrative enclosure with four principal gates.
• Evidence limit: the plan is reconstructed mainly from medieval written descriptions because the early structures do not survive above ground.

Why did al-Mansur build a new capital?

The Abbasids came to power through a movement rooted in Khurasan and Iraq, while Damascus remained closely associated with the Umayyads. A new foundation let al-Mansur shape court space, security and political symbolism around the new dynasty. Central Iraq also offered access to the Tigris and Euphrates systems, irrigated agricultural land, routes to the Persian Gulf and connections toward Iran, Central Asia, Arabia and the Mediterranean. Earlier imperial capitals, including Ctesiphon, had occupied the same broad region. The choice was therefore political, logistical and environmental rather than the result of one astrological anecdote.

Where was the city founded, and what existed before?

Al-Mansur selected a site on the western bank of the Tigris in central Iraq. Medieval sources knew an older settlement called Baghdad, but the Abbasid project transformed the area into a new imperial center. The official name Madinat al-Salam appears on coins and in administrative usage, while Baghdad became the durable common name for the metropolis. Claims for an exact founding day vary in later accounts. The secure historical anchor is the start of the great building program in 762, not a modern birthday ceremony with perfectly settled hour and coordinates.

What did the Round City look like?

Yaqubi and other medieval writers describe a huge circular or rounded enclosure protected by a moat, outer rampart and inner wall. Four gates faced routes toward Kufa, Basra, Syria and Khurasan. Broad avenues led inward through monumental passages. At the center stood the caliph's palace and the main mosque, surrounded by open and controlled court space. The plan expressed hierarchy and access: roads connected the empire to a guarded political center. Details such as exact diameter, wall height and building sequence differ across reconstructions and should be presented as estimates rather than surveyed measurements.

How can historians reconstruct a city that disappeared?

The early enclosure has not survived as visible ruins beneath modern Baghdad. Historians therefore compare descriptions by Yaqubi, al-Khatib al-Baghdadi and other authors, later topographic references, route names, coins and the geography of the Tigris. Guy Le Strange's influential 1900 map organized this evidence and still shapes popular diagrams, but it is a scholarly model, not an archaeological site plan. The safest image caption says interpretive reconstruction. It should not claim that every house, gate tower or street block is known exactly.

Baghdad quickly grew beyond the circle

Madinat al-Salam was a palatial and administrative foundation, not a container for the entire population. The Karkh market district developed to the south, Harbiyya housed military and residential communities to the north, and Rusafa grew on the eastern bank. Al-Mansur himself later used the riverside palace of al-Khuld, while successors created other residences and urban nodes. Within decades, economic and social gravity no longer sat only inside the circle. 'Round City' accurately names the original court core but misleads when used as the shape of all medieval Baghdad.

Did the foundation instantly create the Golden Age?

The city supplied political concentration, markets, patronage and routes that later supported major book, translation, medical, mathematical and geographic activity. Those developments unfolded across generations. Scholars worked in several institutions, homes, courts, hospitals, libraries and workshops; many came from outside Baghdad or never lived there. Paper production, multilingual translation and scientific sponsorship expanded through specific later networks. The foundation of 762 was an enabling urban event, not a switch that produced every achievement commonly grouped under the Islamic Golden Age.

What does material evidence add?

Coins can confirm rulers, dates, mints, titles and monetary practice. Manuscripts preserve later descriptions and the reception of Baghdad's image. Archaeology at Samarra offers comparative evidence for Abbasid houses, palaces and decoration because early Baghdad itself is difficult to excavate. Each source has a boundary. A coin dated 762 does not draw the Round City; a ninth-century text is not a construction photograph; a model based on both remains an interpretation. Strong history comes from combining them without asking one object to prove everything.

Common claims that need qualification

• 'There was nothing at Baghdad before 762': an older settlement name existed, but al-Mansur created the imperial city.
• 'All of Baghdad was a perfect circle': the circle was the original court enclosure; the metropolis spread well beyond it.
• 'Modern diagrams show excavated streets': most are textual reconstructions influenced by Le Strange and later scholarship.
• 'The House of Wisdom occupied the central palace from day one': translation institutions and labels developed later and remain debated.
• 'The city stayed unchanged until 1258': residences, markets, river channels and political centers shifted repeatedly.

How to research the Round City responsibly

Begin by separating the name Baghdad, the official Madinat al-Salam enclosure and the wider metropolis. Label every map as a reconstruction and identify the medieval description behind it. Compare dates in AH and CE without manufacturing an exact modern timestamp. When discussing intellectual history, name the later patron, translator, hospital, manuscript or workshop instead of attributing all knowledge to the city's geometry. This method keeps al-Mansur's extraordinary urban project visible while respecting what has been lost.

Related research guides

• Islamic Golden Age history timeline: Place the early Abbasid transition, Baghdad and Central Asian exchange inside a source-labeled chronology of institutions and learning.
• Islamic history timeline: Connect this event cluster to the wider chronology of Muslim communities, caliphates and regional powers.
• Abbasid Revolution, 747-750: Trace the Khurasani coalition, Abu Muslim, black banners, westward campaign and the limits of simple ethnic explanations.
• Battle of Talas and the papermaking story: Separate what can be said about the 751 encounter from later claims that one battle single-handedly moved paper west.
• House of Wisdom in Baghdad: Continue from the city's foundation to translation networks while avoiding the myth of one universal academy destroyed in a single night.
• Al-Khwarizmi, algebra and algorithms: Follow one scholar associated with Abbasid Baghdad through surviving works, uncertain biography and later Latin reception.
• Fall of Baghdad in 1258: Compare the city's foundation with the later siege and keep library-loss claims tied to specific evidence.
• Al-Biruni, measurement and cross-cultural study: Explore a later Central Asian scholar whose methods show that exchange cannot be reduced to one battle or one court.
• Jabir ibn Hayyan and the Jabirian corpus: Connect early Abbasid material traditions with a corpus whose authorship and later Latin reception require careful separation.

Sources

• Smarthistory: The founding of Baghdad: Used for al-Mansur's site choice, the 762 start, Yaqubi's description, the circular enclosure, four gates and expansion outside the court city.
• Cambridge World History: Baghdad, an imperial foundation: Used for the distinction between the original palatial city, its rapid transformation and the wider metropolis of 762-836.
• The Metropolitan Museum of Art: The Art of the Abbasid Period: Used for Baghdad as the circular City of Peace, the eastward shift of the Abbasid center and later Abbasid urban-artistic context.
• UNESCO: History of Civilizations of Central Asia, Volume IV: Used for al-Mansur's selection of the Tigris site, the Madinat al-Salam name, the 762 foundation and Baghdad's international population.
• UNESCO World Heritage Centre: Samarra nomination dossier: Used for comparison with Samarra and for the dossier's statement that al-Mansur built Baghdad's lost Round City in 762.
• Library of Congress: Al-Idrisi and medieval geography: Used for Baghdad's later place in Abbasid geographic and translation traditions without claiming that all scholarship began at the city's foundation.
• British Museum: Abbasid coin dated from 762: Used as precisely cataloged material evidence from the foundation period while keeping coin date, mint and city plan as separate claims.