The city of Baghdad is the economic, cultural and political capital of the modern nation-state of Iraq. Situated on the banks of the Tigris River, it lies at the northwest end of the alluvial plain that is home to 75% of Iraq's population. As such, its location is in the heart of Ancient Mesopotamia, where the some of the first recorded instances of irrigation and a sedentary agriculture fomented the Sumerian civilization. The political community of Baghdad, however, dates back to the mid-eighth century CE. 

As the capital of the Abbasid caliphate, Baghdad wielded the greatest political power in the Islamic world from the middle of the eighth century until the middle of the tenth. The revolution that brought the dynasty to power coincides with most accounts of the city's founding in 762, though pre-Islamic texts - including the Talmud - mention a significant, if modest, market town at this location. The second Abbasid caliph Mansur succeeded his brother Saffah (reg. 750-754/132-136 AH) in 754, and by 762, Mansur had commissioned the construction of a capital for the new regime, moving political control from Kufa to his new, defensible city. Baghdad remained the Abbasid capital from 762 until 1258 CE. The perfect circle that delimited the city was made of a thick rampart surrounded by a moat and an outer wall. Arab historians of the day remarked that the Round City's layout was unique, but it was not without precedent. Scholars agree the circular morphology reflected the Sasanian influences on Baghdad's original urban design. The circular plan of the city is reminiscent of Firouzabad in Fars. 

Mansur's choice of Baghdad as his capital reflected his desire to maintain political and cultural connections with the eastern as well as western hinterlands of his empire. At each quadrant of the circle stood an impressive gate leading to Khurasan, Basra, Kufa and Syria. The Tigris would facilitate trade from the north, the south and the sea. Furthermore, the extant Mesopotamian canal system was developed; the waters of the Euphrates irrigated the remarkably fertile soils west of Baghdad.

Historians speculate that during the reign of Harun al-Rashid (842-847/227-232 AH) Baghdad was the largest city in the world, with a possible population of between 700,000 and 1,000,000 inhabitants - a cosmopolitan mix of migrants that included Arabs, Persians, Jews and Indians, among others. During this period, this center of civilization witnessed huge scientific, theological and cultural advances, such as al-Khawarismi's invention of algebra and the poetry of Abu Nuwas. But Harun's reign is most famous for the ways it was mythologized centuries later in 1001 Nights.

At Harun's death, early signs of the eventual disintegration of the Abbasid dynasty were beginning to appear, and a new capital city was created at Samarra in the 850s. Shortly thereafter, Baghdad was reinstated as the capital. Abbasid Baghdad remained an important center of Islamic cultural life until the mid-thirteenth century. But by 945, the growing tension between provincial governors and Turkish generals led to a power vacuum that was filled by the Buwayhids, who sold the empire to local warlords piece by piece. Baghdad's influence waned. Significant Abbasid architecture in Baghdad includes the Abbasid Palace in the Q'ala, minarets of the Qumriyya and Khatafin Mosques and Bab el-Wastani (Wastani Gate). 

When the Seljuk General Tughrul Beg marched into Baghdad in 1055, he declared himself the ruler of the Muslim world. For forty years, Baghdad experienced a renaissance under the Seljuks, with the establishment of the prestigious Nidhamiya school and a revival of Persian culture, but the Seljuks' power was sapped by the First Crusade in 1095. The Abbasid Caliphs and the Seljuk Sultans vied for power throughout the next century, and the Abbasid Caliph al-Nasr finally freed Baghdad of Seljuk Turk influence by 1186. The Abbasid restoration did foster specific cultural milestones, such as the construction of the extant Mustansiriya Madrasa in 1233 (an important Sunni theological college that was incorporated into Baghdad University in 1962), but the Caliphs' contributions to Sunni posterity exceeded their political and military acumen.

A series of bloody dynastic and sectarian convulsions were to define the next few centuries, which witnessed the short-lived reigns of the Jalayrid, Qara-Qoyunlu, Aq-Qoyunlu and Safavid dynasties. Baghdad was destroyed more than once in this period, notably by Timur (Tamerlane) in 1401, and the city's Sunnis were massacred by Safavid fanatics in 1501. This genocide attracted the fury of Sulaiman the Magnificent in Istanbul, who rode to Baghdad and successfully established Iraq as Ottoman territory.

For the next four hundred years - with the exception of a sixteen year insurrection by Safavid Persians starting in 1622 - Iraq would remain an Ottoman province of limited international significance, named the "Principality of Baghdad". Between 1869 and 1872, Ottoman governor Midhat Pasha applied Tanzimat reforms to Baghdad. He instituted legal reform, imported a printing press, started a newspaper, and built schools and hospitals. He divided the province into three governorates: Mosul, Baghdad and Basra (which included Kuwait). The Tanzimat reforms had significant town planning implications: for the first time in its history, wide, straight thoroughfares could be cut into the existing urban fabric. Significant Ottoman architecture in Baghdad includes the Jaylani Complex (1534/940 AH) and Ahmadiya Mosque (1795/120 AH).

In 1908, the revolution of the Young Turks spawned Arab nationalism in Iraq. While the Young Turks' ideology sought the imposition of a Turkish identity on all Ottoman subjects, the collateral effect in Iraq was the birth of pan-Arabism.

By the early 20th Century, the British, who had established a trade post in Basra as early as the 17th Century, controlled both the southern route to India (via the Red Sea) and the northern one (via Afghanistan). The middle road, through Baghdad, was much shorter. The British invaded Iraq from the south during WWI, battling German and Ottoman forces on the push north to Baghdad in order to gain control of Iraqi oil and trade routes. The British installed the King of Iraq in Baghdad in 1921. Baghdad was named the official capital of the new nation-state. Even when Iraq was admitted to the League of Nations in 1932, with the British Mandate formally over, British influence remained until the overthrow of the monarchy in 1958. 

The coup d'etat of July 14th, 1958, sought to assert an Iraqi identity rather than an ethnic or sectarian one: Baghdad's new government was ruled by a three-man sovereignty council comprised of a Shia, a Sunni and a Kurd. Freedom of the press, equal rights for the Kurdish community, and women's suffrage were enshrined in law. 

Throughout the 1950s, a growing population was exerting pressure on the existing urban fabric of Baghdad, and the governments of the day conceded that modern planning interventions seemed the best way to respond. At the end of World War I, Baghdad's population was reduced to 200,000. By 1965, this figure reached 1.62 million. In 1955, Doxiadis Associates of Greece (responsible for the planning of Islamabad in 1965 and Riyadh in 1972) were commissioned to produce a comprehensive modern plan for the city, which resulted in the razing of many squatter settlements and the creation of large peripheral housing projects.

In 1963, a coalition of Arab nationalist parties seized power, and the Ba'ath Party rose to supremacy through yet another coup in 1968. Saddam Hussein Abd al-Majid al-Tikriti was appointed deputy of the new Ba'ath leadership. Under the Ba'athists, the Doxiadis plan for Baghdad was replaced with a plan from the Polish firm of Polservice, who advocated high-rise housing as a solution to Baghdad's housing crisis. Throughout the 70s, the price of oil buoyed unprecedented building construction in Baghdad, during which time local architects could collaborate with international consultants such as John Warren and the Architect's Collaborative. Notable examples of architectural modernism in Baghdad include Le Corbusier's Saddam Hussein National Gymnasium and Realisation Scolaire Architectes' National Film Centre (both 1981/1401 AH). 

The Iran-Iraq War (1980-1988) slowed progress, though large, state-sponsored building projects continued in Baghdad and across the country. Significant architectural projects in Baghdad since this war have been dominated by vast monuments to the Iraqi war dead and elaborate renovations to Hussein's palaces. In 1990, the US-led Gulf War that aimed to liberate Kuwait from an Iraqi invasion did not advance to Baghdad, but basic infrastructure in the city was systematically disabled. The sanctions imposed on Iraq thereafter further crippled Baghdad, virtually eliminating the middle class in the process. On the 20th of March, 2003, a new US-led effort to topple Hussein's government did not shy from attacking Baghdad directly. Baghdad fell within twenty days. The Coalition Provisional Authority, which governed the country until May 2004, maintained the well-defended military 'Green Zone' as the core of administrative activity. Outside of the central zone, which is centered on Hussein's palaces, violence remains a daily reality for Baghdadis. The city's monuments and objects of archaeological or art historical significance are under threat. The looting of Iraq's Archeological Museum was highly publicized after the fall of Saddam Hussein's regime. But Iraq's National Library and Archives suffered even more devastating losses. As of April 2007, best estimates for Baghdad's current population are 5.1 million, which is just under a fifth of Iraq's total population of 26.7 million.

Sources:

"Baghdad Renaissance Plan." Arcadd.com. Last modified 2004. http://www.arcadd.com/baghdad-cbd.htm [Accessed October 6, 2006; inaccessible as of May 8, 2014.]

El-Sheshtawy, Yasser. Planning Middle Eastern Cities. London: Routledge, 2004.

Le Strange, Guy. Baghdad During the Abbasid Caliphate. Westport, CT: Greenwood Press, 1983.

Levy, Reuben. Baghdad Chronicle. Philadelphia: Porcupine Press, 1977. 

Polservice Consulting Engineers. Comprehensive development plan for Baghdad 2000. Warsaw: Polservice Consulting Engineers, 1973. 

Rosenberg, Matt T. "Largest Cities Throughout History." About.com. Accessed October 6, 2006. 

http://geography.about.com/library/weekly/aa011201a.htm.