2. Seoul

Population: 23,800,000
Country: South Korea

Seoul is the largest city in South Korea, its capital and the unquestioned economic, political and cultural hub of the country. Seoul suffers from a partly unwarranted reputation for pollution and traffic jams. These days, strict emissions laws have brought the pollution under control and, while traffic jams do still snarl up Seoul's streets at rush hour, the extensive subway network means that the traveler can easily shortcut through it almost all of the time. With beautiful palaces, great food and a hopping nightlife.