Projected Population in 2015: 35.5 million



Population in 2005: 35.2 million

Originally called Edo, this city did not amount to much until 1603, when Shogun Tokugawa Ieyasu made it his home. After Japan's Meiji Restoration in 1868, the emperor moved in and changed the name to Tokyo. The city was devastated by an earthquake in 1923 and by U.S. bombers in 1945. Despite these setbacks, and despite the damage inflicted by Godzilla in numerous films, Tokyo eventually surpassed New York to become the world's biggest city--a title it will retain at least until 2015.