“Architects think that they are the ones who control the way a city looks, but it’s really the developers,” said publisher Andrea Monfried, founder of Andrea Monfried Editions, whose latest book is “Developing: My Life” by William Zeckendorf Jr. with Joan Duncan Oliver.

Zeckendorf, a modest man who never liked talking about himself, was persuaded to write a memoir focusing on the projects he had done instead of his own interior life, first began working on the book in 1995. He died in 2014.

On Wednesday evening his widow, Nancy Zeckendorf, and her stepson, Will Lie Zeckendorf, held a book party at 50 United Nations Plaza in Manhattan to celebrate the launch of the tome. Among the guests were I.M. Pei, his daughter Liane and Robert A.M. Stern.

Will pointed out in his formal remarks at the party that his father, the son of the celebrated developer William Zeckendorf Sr., had a relatively short career — running his own business only between 1972 and 1994 — but that he had made a major impact on New York during that time.

“He would call me to ask about certain deals,” said Will, recalling a time when his father was working on the book. He observed later that the difference between what he and his brother, Arthur, do as developers and what their father did is that they generally work on only one building at a time rather than six or seven.

For her part, Nancy noted that people often ask whether her husband actually wrote the book. “Yes,” she said. “He wrote it himself with his computer and two fingers….He used to say that he considered himself a failure. But we didn’t have a list of the projects he had done. Do most businesses have a list?” When they counted up the projects he had actually completed, his widow noted, “He never called himself a failure again.”

William Zeckendorf Jr. created, worked on or owned 28 buildings and plazas, among them the apartment buildings The Columbia on the Upper West Side, Zeckendorf Towers in Union Square, the Cosmopolitan and the Vanderbilt in Midtown and Queens West in Queens. He was also involved with a number of hotels, including the Crowne Plaza Hotel and the Four Seasons.

The developer’s favorite part of the business, his widow pointed out, was what developers refer to as “assemblage,” putting together the parcels of land and property that are needed to create a large new building or plaza. This requires a considerable amount of patience and, often, clever horse-trading. When he decided to buy the Delmonico, for instance, he was able to purchase it partly by persuading his father to give one of the sellers — who had just lost her own German shepherd — his dog Mozart.

And the business can be full of surprises. When he was creating the Belaire, a mixed-use building that he built from the ground up, his construction crew had been digging a large hole to create the foundation for the building, when a nearby edifice began to list.

“It turned out that the 18-story apartment house next door to our site went up in the 1960s, it wasn’t built to code,” Zeckendorf wrote. “Instead of resting on proper foundations, it was sitting on mud. It had been leaning against the garage foundations on our site for support, and when we tore down the garage, there went the support.”

The result: By law, the developer had to shore up the foundation of the neighboring building before finishing the job, adding four months to the construction schedule. In the end, though, he wrote, “The Belaire was another financial home run.”