Đà Nẵng is one of the major port cities in Vietnam and the biggest city on the South Central Coast of Vietnam; the city is situated on the coast of the South China Sea, at the opening end of the Hàn River. Đà Nẵng is the commercial and educational center of Central Vietnam, with a well-sheltered, easily accessible port; its location on the path of National Route 1A and the North–South Railway makes it a hub for transportation. It is located within 100 km of several UNESCO World Heritage Sites, including the Imperial City of Huế, the Old Town of Hội An, and the Mỹ Sơn ruins. The city was previously known as Cửa Hàn during early Đại Việt settlement, and as Tourane (or Turon) during French colonial rule. It is the third biggest economic center in Vietnam (after Ho Chi Minh City and Hanoi). Đà Nẵng is listed as a first class city, and has a higher urbanization ratio than any of Vietnam's other provinces or centrally governed cities. In terms of urban population, Đà Nẵng is the fifth largest city in Vietnam.