Harry Macklowe wanted to go higher. “Another story up?” he offered with a smile.

Mr. Macklowe, a developer with a habit of injudiciously reaching for heights, was pointing to a small steel ladder at the job site of his latest and most ambitious project: a luxurious building at 432 Park Avenue, which, upon completion, will be, at 1,398 feet, the tallest residential tower in the Western Hemisphere. He had already shot up 23 stories in a rickety construction hoist and climbed six more on a makeshift metal staircase. Now, in his pinstriped suit and at 76 years old, he shinnied up the ladder (“Follow me!”) to the 30th — and last completed — of what will be 84 floors.

“This,” he said, arriving at the top, with the ocean and Connecticut in view, “is a once-in-a-lifetime opportunity. There’ll never be another job like this one. It’s going to live on for a very long time after I’m gone.”

While it may be true that Mr. Macklowe’s building — with its soaring city vistas, its catering department and its $95 million penthouse that will look down on the helicopters fluttering below — is indeed the project of a lifetime, it is also true that he has undertaken it only now, in what amounts to his third or fourth professional life. The risk-addicted builder has been up and down so often, and so violently, over the years that his career of half a century in New York City real estate has the dizzying topography of the Himalayas.

Mr. Macklowe has flirted with disaster several times — during the recession of the early 1990s, the collapse of credit markets in 1998 and, most gravely, the recent subprime mortgage crisis. But on each occasion, he has somehow tiptoed off the precipice and managed to survive. Not that he admits to the indignity of ever having fallen — or even the necessity of getting back up.