The city planner Edmund Bacon once described Beijing as “possibly the greatest single work of man on the face of the earth.” When he was there, in the nineteen-thirties, you could still see that the city, from the walls surrounding it to the emperor’s Forbidden City at its heart, was conceived as a totality?a work of monumental geometry, symmetrical and precise. Even the hutongs , the warrenlike neighborhoods of small courtyard houses set along alleyways, which made up the bulk of the city’s urban fabric, were as essential to Beijing as the temples and the imperial compound, which has the same intricate mixture of courtyards and lanes. Bejing was all of a piece.

It couldn’t last forever, and it didn’t. Mao Zedong tried to change Beijing into an industrial and governmental center, putting up factories and ponderous administrative buildings. But now Mao’s Beijing is nearly as much a part of the past as the Forbidden City. The factories are being pushed to the outskirts, and in their place the city has developed a skyline. It isn’t like the height-obsessed skyline of Shanghai, or the tight, congested skyline of Hong Kong. In Beijing, the towers are sprinkled all over the place. Most of them are mediocre, and some are ridiculous?a few have pagodalike crowns, to satisfy a former mayor who insisted that new buildings appear Chinese?but a handful are among the most compelling buildings going up anywhere in the world. In Beijing, the latest trend is architecture that will force the world to pay attention, and the result is a striking, unmistakably twenty-first-century city, combining explosive, relentless development with a fondness for the avant-garde. Beijing is as ruthlessly unsentimental today as it was in Mao’s time, with little patience for history if it gets in the way of development, and yet the city doesn’t feel as if it were defined solely by growth, like Shanghai, or like the kind of entirely manufactured environment that you see in Dubai. When I visited Beijing recently, the architect Ole Scheeren said to me, “I think Beijing is incredibly strong in its ability to completely override its own history and yet not surrender its identity.”

Scheeren is the co-architect, with Rem Koolhaas, of the most eagerly awaited building in Beijing, the headquarters of the Chinese television network CCTV, a monumental construction that has become world-famous long in advance of its completion, scheduled for late this year. A vast structure of steel and glass, it is a dazzling reinvention of the skyscraper, using size not to dominate but to embrace the viewer. The building will contain more office space than any other building in China and nearly as much as the Pentagon, but, as skyscrapers go, it is on the short side, with just fifty-one floors. Looking from a distance like a gigantic arch, it is a continuous loop, a kind of square doughnut. Two vertical sections, which contain offices, lean precariously inward, connected by two horizontal sections containing production facilities, one running along the ground, the other a kind of bridge in the sky. When you get closer, you see that each horizontal section is made up of two pieces that converge in a right angle. The top section, thirteen stories deep, is dramatically cantilevered out over open space, five hundred and thirty feet in the air, and it seems to reach over you like a benign robot. The novelty of the form?some Beijingers have taken to calling it Big Shorts?takes time to comprehend; the building seems to change as you pass it. “It comes across sometimes as big and sometimes as small, and from some angles it is strong and from others weak,” Scheeren said. “It no longer portrays a single image.”

You might think that, like a good deal of Koolhaas’s work, the building is as much showmanship as architecture, but it evinces a quiet, monumental grandeur. Some of that is due to the color of the glass, which is a soft gray, almost perfectly echoing the overcast Beijing sky. Around the glass, the diagonal grid of the building’s steel framework is visible, the lines getting denser in the cantilever, where the structural stresses are more extreme. Scheeren told me, “I had the fantasy that the facade would disappear against the gray sky and you would be left with only the black grid.”

Like the CCTV building, a new development designed by the New York architect Steven Holl?a cluster of linked apartment buildings?displays a boldness that would be unlikely to escape compromise in a Western city. And, like the CCTV building, its most notable feature is a bridge?or, rather, bridges?high in the air. Holl has built eight squarish towers and one round one (which will contain a hotel), each about twenty stories tall. The residential towers have identical aluminum facades in a grid pattern, with square windows set back and edged in bright colors that Holl says he took from Buddhist temples. Holl placed the towers in a ring around the property, connecting them with glass-enclosed bridges at various heights?a kind of public, or semi-public, street in the sky running all the way around the complex. Some bridges start on one floor and end on another, so that you walk up or down a ramp?a hill in the sky. Each bridge contains some facility that the tenants share?a gym, a cafe, a bookstore. The most eye-catching has a swimming pool, which feels as if it were floating in the air, seventeen stories above Beijing.

The idea of the street high above the city is intended to counteract the sense of isolation that high-rise living usually brings, and to create an incentive for residents to walk around the complex. “In Beijing, to go anywhere means taxis and traffic jams and pollution,” Hideki Hirahara, the project architect in Holl’s Beijing office, told me as we walked around the site, where construction crews were just beginning to enclose the steel bridges. “We wanted to create all city functions inside the project.”

The bridges are spectacular, inside and out, and one can imagine that there will be an allure to walking in the air from tower to tower that having a cup of coffee on the ground can’t match. But there’s a hitch. This clever prototype for a city without streets is also an admission that the traditional street-based city doesn’t have much of a future here. As an attempt to bring avant-garde ideas to high-rise housing, the development is impressive, but at another level it’s not unlike the gated apartment compounds that now fill much of Beijing’s rapidly developing outskirts. The twenty-first-century equivalent of the ancient hutongs is a kind of skyscraper suburbia. You drive there, and then you get back in your car every time you go outside?exactly the model that planners in the United States have been trying to get away from in recent decades.

In this context, it’s not surprising that another example of big-ticket Western architecture in Beijing?the National Center for the Performing Arts, by the French architect Paul Andreu?is about as disconnected from the street as possible. It’s an ovoid of reflective glass set in an artificial lake and designed to look as if it were floating on water; there isn’t even a door, lest the purity of its shape be disturbed. You descend to a sunken plaza beside the pool, walk through a tunnel under the water, and ride up an escalator to find yourself inside the ovoid. There’s excitement in being under a huge, curving roof that shelters three different halls, but, in general, the entrance, striving for high drama, comes off as silly and cumbersome. The Chinese refer to the building as the Egg.

Locals call Beijing Tan Da Bing , which means Spreading Pancake. Since 1991, it has gained, on average, nearly three hundred thousand people a year, and by the end of last year it had a population of around seventeen million. Old Beijing?designed for pedestrians and imperial processions but not much in between?has turned out to be a bad framework on which to construct a modern city. It has too few conventional streets, and they are spaced far apart. There aren’t many traditional city blocks. In the days when Beijing was famous for swarms of cyclists, its unsuitability for automobiles didn’t matter; now that the Chinese have cars, Beijing has gone in one generation from emanating an ancient spirit to feeling like Houston. When I visited three years ago, I thought that its problem was a compulsion to repeat the mistakes of American cities. Now the picture is much less clear. Crowding, pollution, and sprawl still define the city, but the new architecture, far from replicating an American mistake, surpasses what most American cities would be willing, or able, to do. This has an effect on the city’s mood: people talk about the new buildings and, whether they approve or not, recognize that such daring constructions would not get built anywhere else.

Beijing is also beginning, slowly, to talk about historic preservation. Wang Jun, a thirty-nine-year-old journalist who was born in southwest China, has become Beijing’s Jane Jacobs, an outspoken advocate of old neighborhoods and traditional streets. “When I started to work, it was the period of Beijing’s most intensive dismantling,” he told me. “I did a lot of investigating, and the city officials were very unhappy, which drove me to more investigating, which made the city officials even more unhappy.” Now, Wang says, city officials invite him to meetings they once refused to let him attend, and the city has begun to put money into renovating some hutongs that would have been demolished a few years ago.

There are urbanists who think that Wang Jun’s position smacks of nostalgia, and that the challenge facing Beijing is to develop a new urban form. “In China, bigness has become the only tool to keep pace with the fast developments,” Neville Mars, a Dutch architect in Beijing, said to me. “The European model of urbanization is outdated, and China proves it. Beijing is a scattered city?how can we patch it back together? The Chinese appear to be in control, but it is really moving too fast for anyone.”

Still, developers have lately begun to grasp the appeal that older buildings have, at least for the rapidly growing professional class. SOHO China, a marketing company that established itself with huge modern residential and commercial complexes in Beijing, is now at work on a retail complex, at Qianmen, just south of Tiananmen Square, that will be built around preserved and reconstructed sections of a hutong ?a kind of Beijing version of Boston’s Fanueil Hall. Zhang Xin, who, with her husband, Pan Shiyi, controls SOHO , told me, “So much has been destroyed. Now what excites me is keeping what is left.” But often what’s left isn’t much, and most of the new complex will have to be built from scratch. Zhang said, “Chinese people don’t like anything old?they want everything new. If someone came from the moon, they would think this is a newer country than America.” She paused. “Maybe that is what Mao wanted,” she said. ?