Hanoi is the capital city of Vietnam. It covers an area of 3,358.6 square kilometres (1,297 sq mi). It is the second largest city in Vietnam, with over eight million residents within city proper and an estimated population of 20 million within the metropolitan area. Located in the heart of the Red River Delta, Hanoi is the commercial, cultural, and educational centre of Northern Vietnam. Having an estimated nominal GDP of US$32.8 billion as of 2018, it is the second most productive economic area of Vietnam, after Ho Chi Minh City.