Rio's a great place for architecture buffs, and an even better place to watch what happens when overconfident urban designers set their hands to the task of urban renewal. For a city so blessed with mountains, ocean, and historical roots several centuries deep, Rio's movers and shakers have suffered from a striking sense of inferiority. As a result, various well-meaning Cariocas have since the early 1900s taken turns ripping out, blowing up, filling in, and generally reconfiguring huge swaths of their city in order to make Rio look more like Paris or Los Angeles or, lately, Miami Beach. The results of these various movements are -- for better and worse -- now and forever on permanent display.

Around Cinelândia -- "Rio Civilizes Itself!" Armed with this slogan and a deep envy of what Baron Haussman had done in Paris, engineer-mayor Pereiro Passos set to work in 1903, ripping a large swath through Rio's Centro district to create the first of the city's grand boulevards, the Avenida Central. So efficient was "Knock-it-down" Passos that the old colonial Rio he set out to demolish can now be found only in the few square blocks around the Travessa do Comércio to the north of Praça XV. Accessed via the Arco do Teles -- an arch built in 1790 to allow passage through a commercial building facing the square -- it's a charming area of narrow cobblestone streets and gaily painted colonial shops, now much missed by civilized Cariocas.

The boulevard Passos created in its stead, however, was also quite graceful. Now renamed the Avenida Rio Branco, it runs from Praça Mauá south past the grand neoclassical Igreja de Nossa Senora da Candelária to what was then the waterfront at the Avenida Beira Mar. The four-story Parisian structures that once lined the street are now found only in photographs, replaced by tall and modern office towers. (Rio Branco remains the heart of Rio's financial district.) The best place to witness the handiwork of these turn-of-the-20th-century Parisizers is on the Praça Floriano, referred to by most Cariocas by the name of its subway stop, Cinelândia. Anchored at the north end by the extravagant Beaux Arts Teatro Municipal, and flanked by the equally ornate Museu de Belas Artes and neoclassical Biblioteca Nacional, the praça beautifully emulates the proportions, the monumentality, and the glorious detail of a classic Parisian square. The Teatro Municipal was in fact explicitly modeled on the Paris Opera House and inaugurated on Bastille Day (July 14) 1909. (Visitors can poke their heads into all of these buildings, but the best place to appreciate the square may well be seated at an outdoor cafe enjoying a nice cold draft.)

Around Castelo -- The next stage in urban reform came in the early '20s, when a group encouraged by public health advocate Oswaldo Cruz, backed by a development consortium, decreed that the hilltop castle south of Praça XV had to go; the 400-year-old castle was a breeding ground, they said, for pox, plague, and other infectious diseases. In 1922, the castle was blown up, the hill leveled and -- starting in the early '30s -- construction begun on a series of government office towers inspired by the modernist movement then sweeping Europe. The first of these -- then the Ministry of Education and Health but now known as the Palácio Gustavo Capanema (Rua da Imprensa 16) -- listed among its architects nearly all the later greats of Brazilian architecture, including Lucio Costa, Oscar Niemeyer, and Roberto Burle Marx, with painter Candido Portinari thrown in for good measure. International architects sat up and took note; other less avant-garde government departments commissioned architects with different ideologies, resulting in a War of the Styles that raged through the remainder of the 1930s. Perhaps the most bombastic counter-volley was the overblown neoclassical Ministerio da Fazenda building (Av. Presidente Antônio Carlos at Av. Almirante Barroso). The resulting enclave of office towers, known as Castelo, lies on the patch centered on the Avenida Presidente Antônio Carlos. Chiefly of interest to architectural buffs, it should be toured only during office hours.

Around Cidade Nova -- Knock-it-down Passos had nothing on Getulio Vargas. On the national scene the Brazilian dictator was creating a new quasi-fascist political structure called the Estado Novo; in his capital city, he set about creating a Cidade Nova to match. In 1940, on Vargas's personal order, a monster 12-lane boulevard was cut through the city fabric from the beautiful N.S. de Candelária Church out through the Campo de Santana park to the northern edges of downtown. Anchoring this new megaboulevard was the Central Station (known officially as the Estação Dom Pedro II, it's worth popping in to see the Art Deco interior), a graceful modern building with a 135m (443-ft.) clock tower that still stands overlooking the city, providing a much-needed reference point in the northern half of downtown. Vargas's plan called for the entire 4km (2 1/2-mile) street to be lined with identical 22-story office blocks. Cariocas, however, seemed to have a limited appetite for Identi-cubes. Only a few were ever built; they can be seen on the block crossed by Rua Uruguaiana. Even 60 years later, much of the rest of this ultrawide boulevard remains effectively vacant. As a silver lining, however, there was lots of space left for architect Oscar Niemeyer to build the Sambodromo, the used-once-a-year permanent Samba Parade Ground. Designed in typically Niemeyer all-concrete style, it stands in the shadow of an elevated freeway, about 1km (1/2 mile) along Presidente Vargas.

Around Aterro -- The next great reconfiguration of Rio came 2 years after the federal capital fled inland to Brasilia. City designers took the huge high hill -- Morro Santo Antônio -- that once dominated the Largo da Carioca, scooped away the earth and dumped it on the beach from Lapa to Flamengo, creating a vast new waterfront park. On the rather raw spot where the hill once stood there arose the innovative cone-shaped Catedral Metropolitana, and at the intersection of the new avenidas República do Chile and República do Paraguai, a trio of towering skyscrapers, the most interesting of which is the "hanging gardens" headquarters of Brazil's state oil company Petrobras. On the waterfront park -- officially called Parque do Flamengo but most often referred to as Aterro, the Portuguese word for landfill -- designers created new gardens and pathways, a new beach, and a pair of modernist monuments: the MAM (Modern Art Museum) and the impressive Monument to the Dead of World War II. Not incidentally, the park also bears two wide and fast roadways connecting Centro with the fashionable neighborhoods in the Zona Sul.

Palaces

There aren't a lot of true palaces in Rio, for the simple reason that the aristocracy wasn't around long enough to build many. But as if to make up for this lack of palaces, Brazilians have taken to granting any number of grand structures the appellation "palace." The Palácio Tiradentes, Av. Presidente Antônio Carlos s/n (tel. 021/2588-1411), for example, was built in 1926, long after the aristocracy had departed. Located at the back edge of Praça XV, this rather overwrought neoclassical structure was built to serve as the Brazilian Federal Legislature, which up until then had been meeting in an old jailhouse. Four years after its inauguration, dictator Getulio Vargas overthrew the government and turned the palace into his ministry of propaganda. Nowadays the building serves as the legislature for the state of Rio de Janeiro. Visitors can tour the permanent display that runs down the outside corridor of the building, but since the text-heavy exhibit is exclusively in Portuguese, there's probably not much point.

Older and more graceful is the Palácio Itamaraty, Rua Marachel Floriano 196, near the Central Station (tel. 021/2253-7691). Built in the 1850s for a coffee merchant with the rather grand title of Baron de Itamaraty, the charming neoclassical design -- the front has pink walls pierced by granite arches -- was sold to the new republican government in 1889 and long served as the ministry of foreign affairs. It has since been converted into the Museum of History and Diplomacy, but this is now closed indefinitely (sem previsão). However, as one small museum display remains open (again in Portuguese only), you do have an excuse to get past the guard (you have to show ID) and wander back to the gorgeous interior courtyard where two ranks of imperial palms flank a long reflecting pond in which jet-black swans swim round.

The most impressive palace in Rio is actually the most modern. Or rather, capital-M Modern. Located in the city's office district, the Palácio Gustavo Capanema, Rua da Imprensa 16 (no phone), was designed and built from 1932 to 1936 by a team of Brazil's top architects, then the best practitioners of modernism in the world. On the team were Oscar Niemeyer and Lucio Costa (the pair who would later design Brasilia), landscape architect Roberto Burle Marx, and artist Candido Portinari, who did much of the tile work that covers the buildings. Supervising as design consultant was Swiss über-modernist Le Corbusier. The result can be underwhelming at first, but that's because 70 years later we've seen a lot of things similar. But when this was built, no one had ever done anything like it. The entire structure has been raised on pilings 40 feet off the ground, creating an open, airy plaza beneath. And unlike later modernists, this team paid attention to the details: The support columns are covered in beautiful marble, the few ground-level walls in intriguing blue-and-white tile -- many designed by Portinari. Ordinary people enjoy the open space thus created. Architectural fans can stand and admire this building for hours.

Churches

Rio is awash with churches, with some 20 in Centro alone. Likely the most impressive church in Rio is Nossa Senhora de Candelária, set on a traffic island of its own at the head of Avenida Presidente Vargas (tel. 021/2233-2324). Although a church has stood on the spot since the 1680s, the current clean and simple neoclassical design dates from a renovation begun in 1775. Particularly worth noting are the huge and ornate cast-bronze doors, the ceiling panels telling the story of the church, and the two large Art Nouveau lamps on either side of the pulpit; they look like cast-iron Christmas trees. Open Monday through Friday from 8am to 4pm, and Saturday and Sunday from 9am to noon.

Worth a visit and much more centrally located is the Igreja da Ordem Terceira de São Francisco da Penitencia, Largo da Carioca 5 (tel. 021/2262-0197). Set on a hilltop overlooking Largo da Carioca, this and the Church of Santo Antônio next door form part of the large Franciscan complex in the city center. The São Francisco church is simply outstanding: Interior surfaces are filled with golden carvings and hung with censors of ornate silver. Open Tuesday through Friday 9am to noon and 1 to 4pm.

On a hilltop all its own is the N.S. de Glória do Outeiro, which can be accessed via the stairway located next to Rua da Russel 300 (tel. 021/2557-4600). It's unique among churches in Rio, thanks to its octagonal ground plan and domed roof. The hill on which it stands was the strategic point taken from an invading French force by the city's founder, Estácio de Sá, paving the way for the settlement of Rio on March 1, 1565. Open Tuesday through Friday from 9am to noon and 1 to 5pm, and Saturday and Sunday from 9am to noon.

Last and most innovative of Rio's significant churches is the Catedral Metropolitana, Av. República de Chile 245 (tel. 021/2240-2669). Some dislike this building, finding its shape disconcerting and its interior dark. I love it. At each of the four cardinal compass points a rectilinear latticework of concrete and stained glass soars upward, tilting inward as it rises. Where they meet at the ceiling there's another stained-glass latticework -- a cross -- shining softly with light filtered in from the sky. The form is modern; the feeling is soaring High Gothic. Open daily from 7am to 6pm; Mass is held Monday through Friday at 11am and Sunday at 10am.

Note: The neighborhood around the cathedral is best visited on weekdays. The area can be unsafe on weekends when the streets are deserted.

The Church That's Not Worth the Hike -- Still impressive, if not quite worth the hype or the long trek, is the Mosteiro São Bento, on a hill on the far-north corner of downtown. Access is via an elevator on Rua Dom Gerardo 40; open daily from 8 to 11am and 2:30 to 6pm. The church itself is a shining example of the Golden Church, the high baroque practice of plastering every inch of a church's richly carved interior in gold leaf. We find it disappointing the way the church forecourt has been transformed into a car park. And the monastery's strategic hilltop has no view whatsoever. Sunday morning Mass features Gregorian chanting by the monks. Service begins at 10am, but arrive early if you want a seat.

Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.