NEW YORK, NY.- The high-rise apartments — some with panoramic views of Singapore’s tropical cityscape — are airy, light-filled and spacious enough to comfortably raise a family. They are also public housing units, and for decades were emphatically affordable, giving Singapore an enviable rate of homeownership.

Now, however, at least a few of the apartments are being sold at a price that would have been unthinkable not long ago: more than $1 million.

“I’m sad to see that — because public housing must equal affordability,” said Liu Thai Ker, the urban planner who gets much of the credit for creating the country’s widely lauded approach to housing its citizens.

Now 86, Liu is considered the architect of modern Singapore because of his role overseeing the development of about half of the more than 1 million apartments that make up public housing in the small and exceptionally prosperous city-state of 5.6 million people.

But in the 1960s, the country’s economic standing was starkly different. It was one of the poorest cities in Southeast Asia, where 3 out of 4 residents lived in overcrowded and filthy slums, in ramshackle houses with tin walls known as “squatters.”

At that time, Liu was working in the New York office of architect I.M. Pei. He had recently graduated from Yale University with a master’s degree in city planning.

“After four years, I felt that America really did not need me; they had way too many architects,” he said. “So I started thinking about coming back.”

He returned in 1969, accepting a job as head of the design and research unit at Singapore’s Housing and Development Board.

One of his main jobs was to create “new towns,” or planned urban centers, for Singapore, even though no one could explain how that would look. So he had to figure it out.

With some research, he decided the new Singapore would include highly self-sufficient neighborhoods with schools, shops, outdoor food stalls and playgrounds.

Liu also wanted to avoid the kind of public housing he had seen in the United States and Europe, where apartments face one another with a central corridor with little light. People with low incomes were living cheek by jowl, creating what he called “ a concentration of poverty.”

He also wanted to spur a sense of community among residents. To figure out how to do that, he asked sociologists to estimate how many families should live in proximity to maximize social interactions. Six to eight was the answer, so each corridor would share six to eight units; that way, neighbors could mingle.

As the public housing following his vision began to be built — and its success to be recognized — Lee Kuan Yew, Singapore’s first prime minister, gave Liu an ambitious goal: resettle everyone still living in the slums by 1982.

By 1985, virtually every Singaporean had a home.

“He used to tell me that the symptoms of a backward city are: one, homeless people; two, traffic jams; three, flooding; and four, polluted air,” Liu said of Lee, Singapore’s founding father.

In the Singapore led by Lee — who was both criticized for suppressing freedoms and celebrated for transforming the country into a global economic power — public housing was about furthering his government’s agenda as well as putting a roof over people’s heads.

The government linked these affordable flats to its pro-family policies, to support for the ruling People’s Action Party and to further integration.

In 1989, a year before he stepped down as prime minister, Lee’s government enacted a policy requiring each block or neighborhood to have a balanced mix of the main ethnic groups in the city — Chinese, Malay and Indian. The goal was to prevent racial enclaves.

Liu said he supported the idea of integration because of the violent racial conflicts that had occurred around the time Singapore became independent, in 1965.

“In the West, the experts condemned it as social engineering because you’re interfering with the freedom of individuals,” Liu said. “But we did that — and succeeded.”

Liu was 6 when he arrived in Singapore in 1944 from Malaysia. His father, Liu Kang, was an accomplished artist in Shanghai who fled to Malaysia during World War II.

After his mother asked him to study architecture to help the family earn money, Liu obtained a scholarship and enrolled in a part-time course at the University of New South Wales in Australia, where he worked and studied at the same time. He graduated with first-class honors.

Liu then headed to Yale, where after graduation, he was offered a choice to go to Harvard University to further study urban design or to work with Pei. He chose the latter.

It was a crucial milestone in his life. From Pei, Liu learned the importance of “flow” and “harmony” in designing buildings, he said, concepts that he put into practice in Singapore.

From 1989 to 1992, Liu was CEO and chief planner of Singapore’s Urban Redevelopment Authority. In 1991, he created the “Concept Plan,” dividing Singapore into five regions, making each one a small city unto its own so people didn’t have to leave an area to go shopping or see a doctor.

“The level of convenience that we experience in Singapore today is largely due to Dr. Liu and his team,” said Heng Chye Kiang, the provost’s professor at the College of Design and Engineering at the National University of Singapore.

After leaving the public sector, Liu did urban planning work in roughly 60 Chinese cities, including Fuzhou, where he met the highest-ranking local official, a man by the name of Xi Jinping. Xi asked him to design the Fuzhou airport, a project that Liu initially turned down because he had not done an airport before.

Several months later, Xi, China’s future leader, came to Singapore and asked Liu to reconsider, according to Liu. This time, he agreed.

At 79, Liu started his own consultancy and is now advising Fiji and the governments of Sichuan and Guangdong in China on urban planning. He works five days a week, which, he said, “slows down the aging process of my brain and my body.”

Liu said one of his main tasks when working for the government on public housing was ensuring that prices would “rise, but slowly,” so homeowners felt they were “in possession of something with commercial value.” But he also wanted to make sure that prices not rise too fast to “make public housing unaffordable.”

Even though record prices on the secondary market have heightened anxiety about the rising costs of living in Singapore, one of the world’s most expensive cities, public housing remains broadly affordable — at least for those who qualify for government subsidies to buy units.

Today, close to 80% of Singapore’s residents live in public housing, and about 90% of the units are owned on a 99-year lease.

In a statement, Singapore’s Housing and Development Board said, “The government remains committed to ensuring that public housing remains affordable to Singaporeans.” The million-dollar apartments sold on the secondary market, government officials have said, make up a minuscule fraction of total transactions; as of May, 54 such apartments have sold for more than $1 million.

Families buying in the secondary market are given housing grants of up to roughly $60,000, but they have to meet an income ceiling.

Starting in the second half of this year, singles 35 and older will be eligible to buy a one-bedroom apartment from the government in any location; before the new rule, they had been restricted to certain areas.

Liu said Singapore’s model could be replicated in other countries, but he acknowledged that his path was smoothed by the government enforcing a law allowing it to buy land at market prices, which made it easier for him to obtain plots for development.

“Most other democratic countries will have difficulty to do that because the landowners will protest,” Liu said.

Asked about any regrets, Liu mentioned two: He should have created bicycle paths for the city, he said, and “preserved a few hectares of the squatter huts with the dirt roads and so on for the younger generation to see.”

He added, “Then they would really know how far we’ve traveled.”

This article originally appeared in The New York Times.