Situated in northwestern Brazil where the mighty Solimoes, Negro and Madeira rivers converge to form the grand Rio Amazonas, Amazonas is the largest Brazilian state, covered almost entirely by the Amazon rainforest. The rivers join at the capital port city of Manaus, which serves as a great base for exploring the area and offers some interesting forest tours and landmarks of its own. Visitors can look forward to taking a boat tour of the Rio Negro's Anavilhanas Archipelago and its hundreds of islands, occupied by a number of indigenous villages. Other popular attractions include the Jardim Botânico Adolpho Ducke in Manaus, the world’s largest urban forest and, also in Manaus, the gorgeous opera house of Teatro Amazonas, built at the height of the rubber boom.