YOU could be in London, Vienna, Paris or Rome. The opera house is as magnificent as any you would find in Europe, except that it is on a smaller scale.
And of course there is the 95 per cent humidity which has faded the heavy, century-old stage curtain, and the canvas, in the shape of the base of the Eiffel Tower, over the high domed roof. Both were hand-painted.
The heat is also a problem, up to 37 degrees Celsius at the height of summer.
But long before air-conditioning came to cool the rich, they would flock here, surrounded by jungle, men in their suits, silk shirts and waistcoats, their wives in gowns imported from France, fanned by servants.
Indeed, if you were not rich and white, you would be denied entry to the driveway, paved in rubber, yes rubber, where the horse-drawn carriages arrived in silence.
It looks ludicrous today, this opera house in the heart of Manaus, capital of the Amazon region of Brazil. For of course no opera is ever held here now, and the old quarter that surrounds it, built by the Portuguese, is decaying from neglect.
The building opposite provided opulent, if somewhat sweltering, accommodation late last century for the stars and musicians who had suffered weeks of sea-sickness travelling from Europe to entertain these rich but culturally deprived colonisers.
Now young, mixed blood Brazilian girls learn ballet there, but are easily distracted from their flexibility exercises, smiling and waving from the upper windows.
But the opera house must have looked more out of place when it was built.
For then, the Amazon jungle was so close that it had to be hacked back, otherwise it would have taken over and covered the building, a masterpiece of snobbery and delusions of grandeur. Materials like marble had to be shipped in from Europe.
Don't believe what your guide tells you about photographs in the Opera House: you are not allowed to take them, he'll say; the flash will damage the stage curtain and roof paintings.
Humidity did that long ago. The real reason is that the souvenir-sellers in the passage would lose business. Their stands are covered with postcards of the interior.
You must not miss Manaus if you visit Brazil. Indeed, if you intend to explore the Amazon, you cannot, for you will start your adventure from here. Varig fly twice-weekly to Brazil from Hong Kong.
You must not miss the Opera House, either. It is a great reminder of man's determination and vanity.
But remember that it was built on the profits of rubber, and rubber, while bringing instant riches to a few, brought misery to many, and eventually to Manaus itself, which thrived on it.
For to build a rubber empire, rubber-tappers were needed, and peasants were lured here from drought-stricken areas with promises of high pay.
One thing the tourist guides are unlikely to tell you is that the rubber-tappers were forced into debt by plantation-owners, from whom they had to buy everything they needed at hugely inflated prices.
It was a form of slavery, though slavery had officially been abolished, and when they tried to run away, pistoleiros, hired by the owners, would hunt them down.
The man who eventually beat the greedy and cruel plantation owners, and brought about the downfall of Manaus was Henry Wickham, an Englishman who smuggled out rubber seeds.
Britain planted them in what is now Sri Lanka, and Malaysia, where they thrived, and Manaus died.
But today Manaus is seeing a resurrection, brought about by tourism, and the old part of this rapidly expanding city, around the Opera House and the jetty, is fascinating if you explore by foot, and about to be saved by renovation.
The suburbs are said to have grown tenfold over the past decade, but the old centre is a living museum of Portuguese (and even British) colonial architecture.
Manaus lies on the Rio Negro, some 10 kilometres upstream from its confluence with the Rio Solimoes, forming the mighty Amazon.
Old wooden vessels lie berthed at the jetty, gradually filling up with Indian traders heading back to the hinterland.
The markets around the harbour display brightly-coloured hammocks, which sell briskly. For if you travel by river, then you must sling your hammock. The journeys are long, hot and slow. No cabins on these river boats. You sleep on deck.
Brazilians seem to show little interest in their wildlife. It is amazing that before 1990 there was no Museum of Natural History in Manaus, which is surrounded by probably the biggest variety of flora and fauna on Earth, in the last vast surviving ecosystem, the Amazon.
The museum was opened by Japanese businessmen who have electronics factories in the area, and it is well worth visiting.
Some of the exhibits of fish from the Amazon are astonishing, as are the insects. Several rooms full, and only a tiny fraction of what is out there in the jungle.
And Manaus also has a Museum of Indian Culture, run by Catholic missionaries. The persecution of the Amazon Indian with the arrival of the white settlers is appalling. But the museum has a comprehensive collection graphically depicting their former lifestyle.
Few now live by hunting and gathering. Most are now poor fishermen, though some customs are still adhered to, such as ceremonial cremations. The museum has an exhibit demonstrating the ritual.
The dead Indian is placed in his canoe with his possessions and masked members of the tribe dance around it while it is set alight.
Six months later, the ashes are mixed with water and tribesmen drink it. They believe his spirit then lives on inside their bodies.
Travel up the Rio Negro from Manaus in one of those slow boats and you may be lucky enough to witness the real thing.
In this week's Review: Alligator hunting and piranha fishing in the Amazon.