Biggest European Cities by Century

In 1002 Al-Mansur was returning to Córdoba from an expedition in the area of Rioja when he died. His death was the beginning of the end of Córdoba. The caliphate disintegrated during a civil war (the Fitna of al-Andalus) between the descendants of the last caliph, Hisham II, and the successors of his hayib (court official), Al-Mansur. In 1031, after years of infighting, the caliphate fractured into a number of independent Muslim taifa (kingdoms). After 1031, Córdoba lost its prosperity and fame and became an isolated city. The "ruling elite" were well known for their "disinterest in the outside world ... and intellectual laziness. (BTW, Destiny is an excellent Egyptian movie about the times of Al-Mansur.)

In response, the Turks began to move into Anatolia in 1073. The collapse of the old defensive system meant that they met no opposition, and the empire's resources were distracted and squandered in a series of civil wars. Thousands of Turkoman tribesmen crossed the unguarded frontier and moved into Anatolia. By 1080, a huge area had been lost to the Empire, and the Turks were within striking distance of Constantinople.

OTOH:

Under the Comnenian dynasty (1081–1185), Byzantium staged a remarkable recovery. With the restoration of firm central government, the empire became fabulously wealthy. The population was rising (estimates for Constantinople in the 12th century vary from some 100,000 to 500,000). Toward the end of Manuel I Komnenos's reign, the number of foreigners in the city reached about 60,000–80,000 people out of a total population of about 400,000 people.

In 1182, all Latin (Western European) inhabitants of Constantinople were massacred. On 25 July 1197, Constantinople was struck by a severe fire which burned the Latin Quarter and the area around the Gate of the Droungarios (Turkish: Odun Kapısı) on the Golden Horn.

etc etc. Better read the long and fascinating history of the city yourself!

(kidding.. put down your torches and croissants.) I'm guessing that the source only goes through 1900. Though I'm wondering with a title like "3000 years of urban growth" why it doesn't extend back to 900 BC. Maybe QM thought it would be too difficult.