Capital of Iraq and centre of Arab learning.
The city of Baghdad was founded in 762, on the site of a Persian village of the same name, by al-Mansur, the second caliph of the Abbasid dynasty. Its layout was designed by the Persian astrologer al-Naubakht and the Jewish astrologer Mashallah.
The original city was of circular design of 2.7 km diametre surrounded by three walls and was basically an administrative complex. It soon became too small for the growing population, and merchant markets developed outside the city walls near the gates. A bridge built from boats connected what soon became the "old city" with the east bank of the Tigris River, and from 946 the seat of the caliphate moved fully to the east bank.
Baghdad's golden age was reached under caliph al-Mahdi, who reigned from 775 to 785, his successor Harun al-Rashid (786 - 809) and al-Mamun (813 - 833). During these years Baghdad was considered the richest city in the world. Al-Mamun established hospitals and an observatory and had works of science translated into Arabic in the various madrasahs.
The decline began with a civil war between Harun al-Rashid's sons, which destroyed much of the old city. Some time around the mid-9th century the caliphs moved the government to Samarra north of Baghdad and left Baghdad to be ruled by their Turkish bodyguards. From 945 to 1152 the Buyids and Seljuqs, successors to the Abbasids, governed from Damascus, and Baghdad went into further decline and ruin.
The final blow, however, came with the sacking of the city by the Mongol Hülegü in 1258, who overran the country, had the caliph and hundreds of thousands of residents killed and the irrigation system destroyed.
Baghdad did not recover from this devastation for centuries. It was relegated to a provincial town under Mongol vassal rulers and sacked again in 1401 by the Mongol Tamerlane. For the next 100 years it was ruled by Turkish dynasties. From 1534 until 1918 Baghdad was, with only short periods of Persian rule, part of the Turkish Ottoman empire.
Modern Baghdad owes its prosperity and most of its appearance to the beginning of steamship travel on the Tigris river after 1860. The Ottoman governors demolished what remained of the city walls and established a modern infrastructure, including new hospitals and schools.
In 1920 Baghdad became the capital of the new state of Iraq, initially under British rule as a mandate of the League of Nations and from 1932 as an independent country.