The capital of Southeast Asia is Hanoi, a city in Vietnam with a population of over 7 million people. It is the second largest city in the country and is located on the banks of the Red River Delta. Hanoi is known for its rich culture and history, having been the capital of Vietnam since the 11th century. It is home to many historical sites, including the Temple of Literature, the One Pillar Pagoda, and the Imperial Citadel of Thang Long.