Projected Population in 2015: 17 million
Population in 2005: 14.3 million

Calcutta was founded in 1690 by the British East India Company, and it later prospered as a port from which the British shipped opium to China. Under the British, Calcutta was India's capital and largest city. These days, it is neither. Its main claim to fame (other than its enormous population) is its predilection for electing communists to run its municipal government. Being true believers, they haven't done nearly as well with their economy as have the lapsed communists who run Shanghai.