Manaus, or Manáos before 1939, or Lugar de Barra do Rio Negro, is the capital city of the state of Amazonas in northern Brazil. It is situated at the confluence of the Negro and Solimões rivers. With a population of two million, it is the most populous city of Amazonas.The city was founded in 1693-94 as the Fort of São José do Rio Negro. It was elevated to a town in 1832 with the name of "Manaus", an altered spelling of the indigenous Manaós peoples, and legally transformed into a city on October 24, 1848, with the name of Cidade da Barra do Rio Negro, Portuguese for "The City of the Margins of Black River". On September 4, 1856 it returned to its original name.Manaus is located in the middle of the Amazon rainforest, and access to the city is primarily through boat or airplane. This isolation helped preserve both the nature as well as the culture of the city. The culture of Manaus, more than in any other urban area of Brazil, preserves the habits of Native Brazilian tribes. The city is the main entrance to visit the fauna and flora of the Brazilian Amazon. Few places in the world afford such a variety of plants, birds, insects, and fishes.It was known at the beginning of the century, as "Heart of the Amazon" and "City of the Forest". Currently its main economic engine is the Industrial Pool of Manaus, the famous Free Economic Zone. The city has a free port and an international airport. Its manufactures include electronics, chemical products, and soap; there are distilling and ship construction industries. Manaus also exports Brazil nuts, rubber, jute and rosewood oil. It has a cathedral, opera house, zoological and botanical gardens, an ecopark and regional and native peoples museums.