Manaus is a port city on the north bank of the Rio Negro. Approximately 1.5 million people live there. Manaus was, in its genesis, a small European fort in the Amazon, established in 1669. By 1850, its population had grown enough to be named the capital of the state of Amazonas. When the rubber industry took off in the 1890's, significant wealth was brought to the city and a grand opera house was built - the Teatro de Amazonas. This period of wealth lasted until 1920, when the rubber industry began to shift toward the Asian markets, and a way to synthesize rubber was discovered. An industrial "re-birth" occurred when the government declared Manaus a duty-free zone (Zona-Franca) as part of a 1970's development plan for the Amazon regions. Today, Manaus manufactures ships, electronic equipment, soaps, and refines petroleum.