At a port in Germany, 150 Steinway pianos are waiting to be shipped to this gateway city for the grand opening of the Juilliard School’s second campus.

The air in Tianjin is so dry that the pianos will require climate-controlled rooms, helping to nearly double the cost of the state-of-the-art campus to $225 million.

The extra money is not coming from Juilliard. The local government is footing the bill. And that could become a problem for officials struggling with debt after an epic spending spree to develop a new commercial center from scratch.

Welcome to Yujiapu Financial District, which promotes itself as China’s Manhattan, but may better be seen as a monument to the breakdown of the Chinese growth model. Four-fifths of the office space stands empty. Construction on other buildings has stopped, leaving skeletons in the sky. A sprawling mall has few shoppers. Inside, a pet store has no animals.

The businesses and residents that local officials had hoped to attract have yet to show up. Juilliard, which is expected to draw in students and their families, will open its doors next fall, a rare Western institution taking a chance on this district.

Zhang Zhiyi works as a recruiter for an online education company in a nearby office building. The lonely landscape has translated into a good deal for commercial renters: New tenants get a full year rent-free. Deals abound, the 28-year-old said: “The other buildings aren’t really full, either.”

Chinese local governments are swimming in debt. By official accounts, that debt totals $4.5 trillion. By unofficial estimates, it could be as large as $10 trillion. No one knows for sure because much of the borrowing for projects like the Tianjin Juilliard campus is rarely disclosed.

China has long borrowed heavily to build and then counted on breakneck economic growth to pay it back. The script: Sell vast amounts of land to developers, borrow to subsidize construction, and jobs and new cities will result. It was a model that helped China build its skyscrapers and high-speed rail lines and ushered in an era of prosperity.

But China is not growing as fast as it used to, and it is not clear that the “build it and they will come” model will save Yujiapu and other places with big debts. The national government now must find other ways to spur growth — without making the debt problem worse.

“China’s economy has depended on building for the future, and there are considerable signs that they have overbuilt,” said Logan Wright, director of China research at Rhodium Group, a consulting firm, adding that debt and overcapacity could hold back growth.

“That probably means much slower economic growth in the next decade compared to China’s recent path,” he said.

Tianjin government officials did not respond to a request for comment.

Tianjin, a coastal city just a short train ride from Beijing, had one of the highest growth rates in China. Its success made headlines, and local officials credited “Tianjin spirit, Tianjin speed and Tianjin benefits.”

Then the economy slowed. And local officials in the Binhai New Area, a special economic zone of Tianjin that includes Yujiapu, admitted they overstated growth. They slashed $50 billion from its original figure for 2016, bringing economic output to $100 billion. Today, Tianjin is one of the slowest-growing regions of China and one of the most financially troubled.

By the broadest measure of borrowing in China, called total social financing, Tianjin’s government, corporations and households owe more than $760 billion, according to an estimate by Rhodium Group. The annual interest owed by all borrowers in Tianjin totaled 12 times its annual nominal economic growth, Rhodium said, citing the most recent numbers.

If Yujiapu really is the Manhattan of China, it has a way to go to catch up to the real thing. Its avenues, some nearly as wide as Broadway, are eerily quiet. Many buildings just a few blocks from the Tianjin Juilliard School remain unfinished. The finished ones are mostly empty.

On one recent weekday visit, the door to the sales office for a hulking, unfinished residential building several blocks from the Juilliard campus blew open in the wind. No one was inside. Many of the six-lane roads in the city lack crosswalk lights, in part because they are not needed.

Across the Hai River from Yujiapu is another ghostlike district, Xiangluowan, where the local government encouraged private Chinese developers to build on their own dime. They did, but no one came. Dozens of the buildings in this district are now collateral for huge overdue loans that are being held by local banks.

For now, Tianjin can continue to borrow for projects like the Juilliard campus because it has a powerful patron in Beijing, said Victor Shih, an associate professor at the University of California, San Diego, and an expert on the Chinese economy. That official, He Lifeng, was once the No. 2 Communist Party official in Tianjin. Mr. He now heads the central government agency that approves all major development projects, meaning he can authorize banks to lend more money to Tianjin.

“If the political will collapses for the Binhai area, then the bank loans will begin to dry up and the whole area is in trouble,” Mr. Shih said.

Officials at the National Development and Reform Commission, the agency where Mr. He works, did not respond to a request for comment.

Despite the empty buildings, the local government keeps borrowing. Last year, Tianjin and entities related to the local government raised $36 billion through new loans, according to data from the People’s Bank of China, the country’s central bank.

Many residents believe Yujiapu’s problems have been overstated and try to cast its emptiness in a positive light. Mr. Zhang, who works for the online recruiter, said technology companies looking for alternatives to expensive places like Beijing and the southern city of Shenzhen could find Tianjin attractive.

“Now, there are quite a lot of internet companies, including some e-commerce platforms,” he said, speculating that these companies could move into his building in the future.

Michael Hart, a real estate consultant in Tianjin, said a resurgence of growth could save the city from its problems.

“It’s like going to see a five-act play,” Mr. Hart said, referring to Yujiapu’s critics, “and you’re halfway through Act 1 and calling it a lousy play.”

For Alexander Brose, the chief executive of the Tianjin Juilliard School, the district will soon benefit from the prestige of the Juilliard name to attract people. On a recent day, he toured the construction site, pointing to what he expected to see next year. Here, a 687-seat concert hall, he said. Over there, a recital space that can hold 299 people. And in the corner, a 250-seat black box theater.

He paused, looking at the hundreds of construction workers welding, hammering and moving steel, and said, referring to the local government, “I think they are looking at this as a feather in the cap of this new project.”