Even if he didn’t possess one of New York’s best-known names, even if he weren’t the scion of an illustrious family that, for exactly 100 years now, has been involved in raising buildings and managing them, even if he hadn’t blazed a noteworthy career on his own in real estate, even if he weren’t quite possibly the city’s most vocal booster as the new chairman for the Association for a Better New York- even if he weren’t any of these things, he would be easy to spot in just about any room he walked into.

That’s because William C. Rudin has presence – and that, in New York especially, counts for a lot. He’s 6 foot 1. He’s a golfer and swimmer, and a daily practitioner of yoga with his wife, Ophelia. He exudes a ready bonhomie, and he has a smile that’s infectious. It’s impossible to have a conversation with him in a restaurant without a dozen people waving or stopping by to say hello, and with Mr. Rudin saying something cheery in exchange. To a reporter who knew his father, the widely beloved Lewis Rudin – who died in September 2001 – there’s something hauntingly similar about father and son, in manner at least.

So to ask him if he missed his father would have been a maudlin question, even unseemly. Of course any son would, especially with such a giant of a man for a father, one who taught him the real-estate business – and perhaps even more importantly, how to deal with people. The reporter recalled how Lew Rudin would sometimes buy a hot dog at the corner of Park Avenue and 52nd Street – the spot is now forever commemorated as Lewis Rudin Way – and stand around chatting with the vendor, and almost anyone who had a moment. He never let on how packed his own schedule was, how he himself was the son of Samuel Rudin – one of New York’s greatest builders – how he was among those responsible for persuading businesses to stay in the city during the financial crisis of the 1970s.

“He did that by articulating the benefits that corporations got by staying in New York,” Mr. Rudin said of his father’s efforts. “He would talk about the highly dependable work force, how New York’s infrastructure was fundamentally sound. His point of view, as articulated to those who considered leaving the city, was simple: It would take you billions of dollars, and perhaps a hundred years, to replicate what’d already been created in New York. The answer to New York’s problems wasn’t declaring bankruptcy. My father understood that you needed to invest in the city – just as we invest in the upkeep and development of our buildings. So he rolled up his sleeves and went to work.”

“My father, and my uncle, Jack Rudin, set the standard for the concept of ‘giving back’ – they always said that you cannot abandon New York, you’ve got to work hard to make sure the city is working right,” said Mr. Rudin, looking in the direction of Jack Rudin, who was lunching at a nearby table. “They transitioned attitudes – they helped everybody understand that this was a city not only for the best and the brightest, but for everybody. That New York was always welcoming to immigrants and other newcomers to American society. I believe that very strongly.”

The reporter thought: So much of the city’s history since Lew Rudin’s grandfather, Louis Rudinsky, escaped the Jewish purges of Czarist Russia and came to America in the 1880s has been intertwined with the history of this one family. Indeed, during a conversation yesterday, Bill Rudin spoke at some length about his heritage, even producing a copy of a deed to 153 East 54th Street, which his great-grandfather, Louis Rudinsky – hometown: Minsk, Russia – signed on January 11, 1905, thus starting what in time would be a real estate empire in New York of 16 office buildings, comprising more than 10 million square feet, and 22 apartment buildings. Now Bill Rudin, who turns 50 on April 20, is president of that empire, formally known as the Rudin Management Company, Inc., which he joined in 1979 after graduation from New York University.

The reporter framed his question this way: “It must be painful to think about your father.”

“I think of him all the time, I think of him every day,” Mr. Rudin said. “When I make decisions, I think of how my father would have made a decision. His pictures are in my office, they are in my home. I think of my father all the time. He taught me the fundamentals, and I’m applying them in what I do.”

What he’s doing these days points to the very essence of how the city is being transformed. Mr. Rudin’s emphasis is on developing downtown Manhattan. He’s championing the resurgence of Lower Manhattan, as he put it, “by giving new life to old properties, both residential and commercial, through converting them into technology-smart buildings.”

Thus, after remaining vacant for many years, 55 Broad Street – a Rudin edifice – became the first building in the city to bring broadband connectivity to every floor. This touched off the trend to make high-tech buildings in the neighborhood. Other Rudin projects include Wired@ 110 Wall St., and the latest one, the Global Connectivity Center at 32 Sixth Ave., in addition to the technologically advanced Reuters headquarters in Times Square. Mr. Rudin is active in the Alliance for Downtown New York.

“When we decided to renovate 55 Broad Street with a 30% vacancy in Lower Manhattan, back in 1995, people said, ‘You are crazy,'” Mr. Rudin said. “But we never take no for an answer. If someone says something cannot be done, then we figure out ways to get it done. Today, downtown Manhattan is one of the hottest markets for investment.”

How hot?

Consider this: A decade ago, property in the area went for between $10 and $15 a square foot. Today, prices of between $300 and $400 a square foot aren’t uncommon.

“I feel better about New York now that I ever did,” Mr. Rudin said. “Foreigners are investing more and more. The Israelis are coming here. The Germans are coming back. We New Yorkers may think that the prices, the numbers, are very high, but foreign investors think they are getting a good deal [because of the declining dollar]. And this is a safe harbor for somebody to invest.”

If this is unabashed New York boosterism, then Mr. Rudin revels in it. These days, the Association for a Better New York – which his father founded in 1973 – is the vehicle for him to emote about the city in which he was born and where he’s spent virtually all his life.

“If the city is doing well, then we are all doing well,” he said.

Such an intense view of the city – and the nexus that his company has to New York – most certainly flows from what Mr. Rudin learned in his formative years. His grandfather had wanted him to abandon college and join the family business early; he even offered to have a desk placed next to his own for his grandson.

“There are times when I wished I’d spent more time with him,” Mr. Rudin said yesterday. “But at least I got to see him during the first 19 years of my own life, and my grandmother, May, for another 15 years after that.”

He vividly recalls the day, in late December 1975,when Samuel Rudin went around his buildings to give holiday gratuities to employees. Bill Rudin accompanied him.

“He was so generous with everybody, and he made everybody feel at ease with him,” Mr. Rudin said.

It was quite possibly the last time that he saw his grandfather alive. A couple of days later, Samuel Rudin died. “It was almost as if he was making a farewell round to be with the people he worked with and who adored him.”

If Samuel Rudin was one of New York’s great builders and developers – he started the Rudin Management Company in 1925 – and if his son Lewis was the one who saved the city from financial ignominy, and if it was the patriarch, Louis Rudinsky who started it all – he wanted to own a building on 54th Street because John D. Rockefeller once stopped off at his downtown store to ask if he sold kerosene manufactured by Rockefeller’s Standard Oil and told Rudinsky that he owned a home on that street – then what is Bill Rudin?

The reporter asked Jack Rudin this question.

“Bill was always a quick learner,” Mr. Rudin told The New York Sun. “He’s leading the family as president of the company. He’s also becoming a very vocal and stable force in the city.”

That same question, when put to Bill Rudin, elicited a more modest response. He was quick to share credit with his cousins, Eric Rudin, Madeline Rudin Johnson, and his chief operating officer John Gilbert and the rest of the Rudin senior management, who, he said, “take the burden off my shoulders in the dayto-day running of the business.” He also lauded the work of his sister, Beth Rudin DeWoody, who looks after the family’s formidable philanthropic interests.

And now there’s a fifth generation of Rudins on the scene: his son, Michael, and his daughter, Samantha, both still at college, but both possible candidates to pursue the Rudin commitment to New York City. There are other candidates, too: his niece and nephew, Kyle and Carlton DeWoody, and several younger cousins.

So what does it feel like to be part of this extraordinary genealogy, the reporter asked Mr. Rudin?

“I wake up thinking how lucky I am that Louis Rudinsky came to New York from Russia – his tenacity, drive, his dream to find freedom in the New World,” he said. “I think about how lucky I am to have had a grandfather like Samuel Rudin, who created a dynasty, who had such tremendous vision, who took such risks. What he understood was connectivity – that in order to succeed you need to connect your business to people.

“And then I think about how lucky I am to have had my father and my uncle, creative giants both, who took their civic and philanthropic commitment to yet another high level. They taught me how important the family is to one’s well-being. They taught me how important it is to communicate with people. It’s all part of my genes, it’s in my DNA. New York is part of my life.”

There are days when Bill Rudin looks out of the windows of his Manhattan apartment and sees New York and its lights and sights, a city that the Rudins, as much as anyone, have helped fashion and sustain for a century. He thinks about the involvement by his wife and himself in creating a charter school for autistic children – in response to the predicament of a friend with an autistic child.

He thinks about how much “balance and perspective” his wife Ophelia brings to his life, layering on a serenity that he learned from his forebears. He thinks of the responsibility that the fortunate of New York have toward those less privileged. He surely thinks that philanthropy isn’t charity but a responsibility. That’s always been the ethos of New York, and certainly of the Rudins.

Like father, like son, the reporter thought: Bill Rudin is his father’s son.