Bissau is the capital city of Guinea-Bissau. The city's borders are conterminous with the Bissau Autonomous Sector. In 2007, the city had an estimated population of 407,424 according to the Instituto Nacional de Estatística e Censos. The city which is located on the Geba River estuary, off the Atlantic Ocean, is the country's largest city, major port, administrative and military center. The last time an official census was held in the country, in 1991, the city/region had a population of 195,389. However, by 2007, the city had an estimated population of 407,424 according to the Instituto Nacional de Estatística e Censos.