From the city, which lies on the Rio Negro, scores of operators run day trips and longer boat tours for visitors wishing to experience the jungle flora and fauna and meet the 'caboclos' (residents of the river towns). The city itself does not have many attractions, apart from some interesting buildings like its opulent and famous opera house, which dates from the height of the rubber boom in 1896. It is a busy place though, being the commercial hub of the state of Amazonas, with its port and markets particularly noisy and crowded. The genuine jungle has receded from the growing city, but it is still possible to find waterways and channels on day excursions that retain the aura of Amazon virgin forest. A popular outing for visitors is to witness the merging of the different coloured waters of the Rio Negro and Rio Solimoes, where they join to form the Rio Amazonas about six miles (10km) downstream from Manaus.