SHANGHAI—The spacious duplex comes with crocodile-skin bedposts, hand-carved bronze doors inlaid with Swarovski crystal lights—and a $45 million price tag.

It is still on the market, but Charles Tong, the developer of Tomson Riviera, a luxury riverfront complex in the heart of the financial district here, says he is having no trouble finding takers for similarly priced units.

“;We're selling three to four apartments every month,”; said Tong, seated in a white Versace easy chair. “;Now, people here want something more luxurious; they'd like a new lifestyle.”;

Everyone agrees China is in the middle of a spectacular real estate boom. The question is whether it is in the middle of a rapidly growing real estate bubble.

When other recent booms collapsed—in the United States, for instance—they depressed entire economies. In China's case, a bursting bubble could affect much of the world. China is the fastest-growing large economy and, so far, a main engine pulling the world out of recession.

Beijing is clearly concerned. Authorities have recently moved to rein in the easy credit that has helped finance China's hyperdevelopment, including making it more difficult for home buyers to take out a second mortgage.

Last year, a record $560 billion of residential property was sold in China, an increase of 80 percent from the year before, according to government statistics that are widely considered reliable. And with prices soaring, developers are scrambling to build more mansions, villas and high-rise apartments with names like Rich Gate, Park Avenue and Palais de Fortune.

Signs of exuberance are everywhere. A Shanghai investor recently bought 54 apartments in a single day; a villa sold for $30 million last year; and in December a consortium of developers paid more than $3.5 billion for a huge tract of land in Guangzhou, one of the highest prices paid for any property, anywhere.

In the city of Tianjin, in north China, developers have created a $3 billion “;floating city,”; a series of islands built on a natural reservoir, featuring villas, shopping malls, a water amusement park and what they say will be the world's largest indoor ski resort.

“;This is wild,”; said Andy Xie, a former Morgan Stanley economist who is now an independent analyst. “;By all the traditional measures, like rental yield, this is a bubble.”;

Speculators are snapping up properties on the expectation that prices will continue to rise, as prices have nearly every year for more than a decade. And powerful developers are working with local governments to transform old cities into urban dreamscapes.

But Shanghai, China's wealthiest and most dazzling city, is the epicenter of the boom. Prices here have risen more than 150 percent since 2003, pushing the price of a typical 1,100-square-foot apartment up to $200,000, according to real estate experts. (Shanghai residents typically earn less than $5,000 a year.)

A buying frenzy has gripped the city, leading to billion-dollar land auctions and long waiting lists.

“;The speed you buy a house here is faster than you buy vegetables,”; said Andy Xiang, an advertising executive who recently put down a large cash down payment to get the right to pay $1.3 million for apartment in the city's exclusive Xintiandi area.

Few residences, though, are as upscale as Tomson Riviera, which consists of four golden-hued towers overlooking the Huangpu River, with a central garden mapped out in the shape of a dragon. The apartment complex's entrance has original artworks by Salvador Dali and well-known Chinese artists. The apartments, a few of which have been decorated by Armani and Fendi, as well as Versace, lease for $7,000 to $17,000 a month—to high-level executives from companies like General Motors and Alcatel.

Those who buy an apartment here tend to be extremely wealthy, like Liu Yiqian, an eccentric Shanghai entrepreneur whom Forbes magazine says is worth about $540 million.

Liu, 47, got his start driving a taxicab in Shanghai but eventually made a fortune investing in the stock market. In an interview this week, he admitted to owning “;hundreds”; of apartments in Shanghai (he said he could not remember exactly how many), including a 6,000-square-foot apartment in Tomson Riviera, which he bought in 2008 for about $11.5 million.

“;I invest in properties,”; Liu said, noting that he also collects art, antiques and jade. “;I think in Shanghai in five to seven years the real estate prices will be even higher.”;

As they try to modulate the market, local and central governments here are walking a thin line. Land sales are a major source of government revenue, accounting for nearly half the cost of China's half-trillion-dollar stimulus program.

Whether the country is in the middle of a bubble has become the subject of a debate. Some economists, like Nicholas R. Lardy at the Peterson Institute for International Economics in Washington, say the housing boom is being fueled by a huge urbanization push that is creating premium-priced houses.

Other analysts say prices are being propped up by greedy developers and government policies that are making housing increasingly unaffordable for the masses migrating to big cities.

Despite the fear of a bubble here, Tong, 38, said his prices were just right, particularly because of so much hidden wealth in China. The publicly listed company is controlled by his family.

“;I have a friend,”; he said. “;She makes maternity clothes. Her company has 20 percent of the world's market share, and they're not even a listed company.”;

Still, Tomson's prices are soaring. The most recent apartment sold for about $2,300 a square foot. The average luxury apartment in Manhattan sold for just under $1,900 a square foot in the fourth quarter of 2009, according to Prudential Douglas Elliman real estate.

Indeed, for the price of a Tomson apartment in Shanghai, a buyer could easily purchase a 6,000- square-foot home in Los Angeles designed by Frank Lloyd Wright ($10.5 million), or a 52-acre site with a 22-room residence in New Canaan, Conn. ($24 million).

But a sales agent at Tomson Riviera says this is the future financial capital of the world, not the dying one.

“;Look at this bronze door,”; said Wang Yaodong. “;That costs $50,000! Look at these Gaggenau appliances. They were made in Germany.”; The glasses were imported from Belgium, the Jacuzzi from Italy. And don't worry about losing your key, he said, “;This lock can read the palm of your hand.”;