Projected Population in 2015: 16.8 million

Population in 2005: 13.2 million

Jakarta is the capital of Indonesia. A port city on the heavily populated island of Java, it has been ruled at various times by Hindu kings, Muslim sultans, Dutch imperialists (who called it Batavia and made it the capital of the Dutch East Indies) and Japanese generals, who conquered it during World War II. Like many coastal megacities, Jakarta will be vulnerable to flooding if global warming raises the sea levels.