The wealth of the primeval forest becomes visible first of all in the architecture of the city. The city enriched and the rubber barons afforded the biggest luxury from Europe, a copy the Grand Opera de Paris - the ''Teatro Amazonas''. Other monuments from this epoch are the ''Mercado Municipal'', a copy of the famous market halls Les Halles in Paris, and the arts center ''Rio Palacio Negro'', located among fascinating Portuguese facades. Today Manaus is a foreign trade zone. Foreign enterprises must pay here no import duties, what guarantees a certain income for the city and the region. Electronics, wood industry and oil refineries have settled in the outskirts in industrial areas. The harbour is the most important trading center for the care of the city with regional, national and international products.The city is pleasant and friendly, although quite hot, and is still a major port, and a good starting point for river tours. The Rio Negro (northern) branch of the Amazon is the color of strong tea, peaty brown and its comparative acidity means few mosquitoes. At Manaus the Amazon rises and falls almost twenty meters between seasons. In May and June it's at its peak, full and very wide, spreading way out into the trees. In November and December it's low; still massive but with sandban http://wikitravel.org/en/Manaus