The New New São Paulo Brazil's largest city is being redefined, as waves of adventurous urbanites with fresh ideas turn some of the most blighted areas of a haves-and-have-nots metropolis into bohemian playgrounds for artists, performers and revelers of every stripe. Tourists arrive in São Paulo and are understandably kind of shocked by the place," Facundo Guerra told me one night in January. We were having dinner at Z Carniceria, an old butcher shop on Rua Augusta that he has turned into a restaurant, meat hooks still hanging above the bar. The area around Rua Augusta used to be a decaying red-light district just a few years ago, but now it is the center of the city's night life, filled with bars and clubs, several opened by Guerra and other investors, that cater to people from across the city's social spectrum. Many of them appeared to be at Z Carniceria that night - tattoos seemed almost mandatory, as if the suit-and-tie elite found in the city's great canyons of skyscrapers inhabited some other land. "But travelers are another matter," Guerra continued. They step foot in the city's labyrinth, and some of them take years to explore. Indeed, to a visitor this metropolis of 20 ­million seems almost defiantly chaotic. But as millions in South America's largest city ascend to Brazil's expanding middle class, something wondrous is happening amid the sprawl. The city is absorbing a new wave of immigrants, from developing countries like Bolivia, ­Colombia and Nigeria, and crisis-­stricken nations like Spain and Portugal. At the same time, ranks of intrepid residents are rediscovering once-neglected parts of their own city, one unpolished gem at a time. In something of a reversal from the city's growth explosion in the 20th century, in which developers abandoned older districts in their rush to build gated high-rises and shopping malls, a new generation of artists, restaurateurs, theater companies and bar owners is focusing on blighted districts that were no-go zones just a few years ago. The result is a culinary and night life scene that ranks among the world's most frenetic and creative, one where the country's legendary social stratification is being shaken and stirred. If there is one representative of this new bohemian effervescence, it is Guerra. Like countless others in São Paulo, he was born somewhere else, in Argentina, arriving in the city as a child with his parents. At 39 he has opened seven bars (although he doesn't drink), he recently completed a doctorate in political science, and he eschews, to the dismay of many Brazilians in his social class, a nanny for his infant daughter. About a decade ago, he bailed on a promising career in marketing for multinational companies, choosing instead the flexibility of being his own boss. From his experience in the corporate world, he knows firsthand how hard many people work in São Paulo, a point of pride among many of the city's professionals. "For better or worse, we define ourselves here by the work we do," he said. That's why we need emancipation at night. No other place captures São Paulo now quite like Rua Augusta. On one end of the street, where it is known as Avenida Europa, car dealerships - seemingly immune to an economy that has slowed from its boom years - sell Lamborghinis and Ferraris, giving way to a stretch of high-end boutiques watched over by imposing guards. Then, abruptly, reflecting an approach to zoning that makes Houston look like Zurich, there is an art cinema, an evangelical church and a store selling skimpy lingerie. Rua Augusta's identity shifts again when it crosses Avenida Paulista - a bustling boulevard where pedestrians can be heard murmuring in an array of languages including Chinese, Arabic and Spanish - and descends into the old center. In this area, called Lower Augusta, crowds spill out of bars and nightclubs onto the sidewalk almost nightly. A few brothels still remain on Lower Augusta, offering a reminder of its past. One neighborhood club, Studio SP, showcases musicians like Bárbara Eugênia, a gifted singer from Rio de Janeiro who swapped her native city's tropical exuberance for São Paulo's gray skies, honing a flirtatiously melancholic musical style. In a break with Rio's historical sway over Brazilian music, the country's new sounds recently seem to have emanated largely from Lower Augusta's bars and clubs, promoting new talents like Criolo, a hip-hop artist from São Paulo's gritty periphery who has been described by the legendary singer Caetano Veloso as "possibly the most important figure in the Brazilian pop scene." "Rio's more closed than São Paulo in terms of experimentation with different musical styles," Barbara Eugênia told me, echoing a sentiment I heard from other Cariocas, as Rio's residents are known, who have followed their star to São Paulo in various walks of life. So many people in São Paulo come from other ­cities that there's a sense we're in the same boat. In all of Brazil, there's no place with the energy of Lower Augusta, where there's a constellation of musicians and composers trying out various ideas. Augusta's transformation, to be certain, stands in contrast to developments elsewhere in São Paulo that seem to reinforce the sense of siege felt by some wealthier residents. For instance, one new upscale shopping mall, Cidade Jardim, has closed its main entrance for pedestrians, discouraging shoppers who do not have the means to arrive by automobile. Such hard edges persist around the city, with pichação, the cryptic graffiti form reminiscent of ancient runic writing, still cloaking buildings in a skyline that stretches to the horizon. And not everyone is thrilled with the way in which Augusta is rapidly changing. "The area was trashy, of course, but at least it was full of life in its own way," said Ana Claudia Veiga de Castro, a historian who lived for years in Lower Augusta in an apartment from which she could often see prostitutes negotiating with potential customers. "Now it's on the verge of becoming respectable, with real estate speculators putting up their towers," she said, referring to the high-rises being built in several locations around Lower Augusta. My fear is that the area will come to resemble other parts of our mistreated city before long. It is a common lament in São Paulo: in the blink of an eye, buildings are demolished and skyscrapers built in their place, almost in oblivion to what stood before them. Another beguiling bohemian area of bars, restaurants and art ­galleries, Vila Madalena, is grappling with this process, as developers race to build residential towers, altering the character of relatively tranquil streets lined with tile-roofed houses. "I'm still able to walk to my restaurant, which is a luxury in São Paulo, but it's shocking to see the area change so fast," said Gabriela Barretto, the owner of Chou, an enchanting small restaurant in a house on Vila Madalena's margins. In her garden she serves Mediterranean-inspired dishes like grilled baby squid with garlicky aioli, and pork ribs marinated in lemon and thyme. Construction sites abound across São Paulo, but it is still possible to stumble upon wonders from other eras. One recent Saturday afternoon, I went to the Estação da Luz, a cavernous train station built by British investors at the start of the 20th century that is now home to the Museum of the Portuguese Language. It's across the street from the Pinacoteca, the venerable public art museum that was masterfully restored in exposed-brick style in the 1990s by Paulo Mendes da Rocha, a winner of the Pritzker Architecture Prize. Arriving at these places, either by metro, on foot or by car, involves exposure to the underbelly of the city's old center. Crack addicts still roam areas not far from the Pinacoteca's masterpieces, and muggings are still a risk. Yet while São Paulo residents fretted about a crime wave in 2012, the city is in fact much safer than it was a decade ago, with far fewer kidnappings than in the past and a homicide rate that has dropped 70 percent since 2001. Cyclists on newly opened bike paths have begun to challenge the supremacy of the automobile. And a so-called clean city law approved in 2006 prohibited outdoor advertising, suddenly giving São Paulo's whitewashed buildings a strangely unsullied look, and allowing massive murals by street artists to ­occupy prominent swaths of the skyline. The dreamy, colorful paintings of the brothers Otávio and Gustavo Pandolfo, graffiti aces who work under the name Os Gêmeos (The Twins), offer prominent examples of this trend, while more subtle street murals like the black line drawings on white facades by Fabiano Gonper provide a cerebral critique of the scramble for wealth and power obsessing many in São Paulo. A good barometer for how São Paulo evolves is the old center, where the Jesuits established an outpost 459 years ago, and in districts surrounding it. What might those missionaries make of São Paulo today? In one area, Liberdade, where Japanese immigrants began putting down stakes about a century ago, newer arrivals from South Korea and China now mingle among the hip crowd at places like Cine Jóia, a 1950s cinema that once showed Japanese movies and is now a music hall with Guerra at the helm. Before entering that haunt one night, I dined nearby at Ban, one of Liberdade's growing number of izakayas, or Japanese pubs. This one was opened by the chef Masanobu Haraguchi, who serves a sublime udon noodle soup with shrimp tempura. Later that night, as I sat drinking a caipirinha at Terraço Itália, near the top of the 46-story skyscraper Edificio Itália, I stared out at the glowing metropolis below and remembered how the legendary French anthropologist Claude Lévi-Strauss generously described the city when he lived here in the 1930s. "I never thought São Paulo was ugly," he wrote. It was a wild town, as are all American towns. São Paulo remains a wildly global city, endeavoring in fits and starts to become safer and less intimidating. It may not be a perfect process, but as Brazil projects its soft power throughout the developing world - and as mega-cities in Africa, Asia and Latin America continue to expand - São Paulo may offer a blueprint of what the future could look like in an increasingly crowded planet: an exhilarating city grasping for solutions to big challenges, where its residents embrace its many pleasures with something approaching abandon.