Hanoi is the capital city of Vietnam. It covers an area of 3,358.6 km2 . The second largest city in Vietnam, it consists of 12 urban districts, one district-leveled town and 17 rural districts. Located within the Red River Delta, Hanoi is the cultural and political centre of Vietnam.
Ho Chi Minh City formerly (and still commonly) known as Saigon , is the largest city in Vietnam, situated in the south. In the southeastern region, the city surrounds the Saigon River and covers about 2,061 km2 (796 sq mi).
Da Nang is a class 1 municipality and the fifth-largest city in Vietnam by municipal population. It lies on the coast of the South China Sea at the mouth of the Hàn River, and is one of Vietnam's most important port cities. As one of the country's five direct-controlled municipalities, it falls under the administration of the central government.
Hong Kong is a city and special administrative region of China on the eastern Pearl River Delta in South China. With 7.5 million residents of various nationalities in a 1,104-square-kilometre (426 sq mi) territory, Hong Kong is one of the most densely populated places in the world. Hong Kong is also one of the three global financial centres and one of the most developed cities in the world.