Nathaniel Benjamin Rosoff, who retired to Miami Beach in 1968, once ran a New York steamship line, married a gorgeous show girl, played tennis on Carl Fisher's home court and attended so many title fights that HBO featured him in a boxing documentary.

He helped his father -- the legendary New York City contractor Samuel ``Subway Sam'' Rosoff -- consult on the Moscow subway system, build workers' housing in the Panama Canal Zone and run a Brooklyn brewery and railroads in Mexico and the Catskills.

On his own, he built subdivisions in the Washington, D.C., area and had a short career as a New York radio announcer.

``Nat'' Rosoff died of natural causes at his Collins Avenue apartment on Sept. 24. The 99-year-old widower and U.S. Marine Corps veteran lived with a caregiver.

`DISTINGUISHED'

Over six feet tall, thin and elegant, Rosoff in his prime ``looked like a Jewish Gary Cooper/Cary Grant,'' said his Miami lawyer, Sam Blum. ``He was distinguished as an old man, always beautifully groomed and nice to everyone.''

Because he and his late wife, Gladyce Denham Rosoff, had no children, Rosoff was especially generous to younger relatives, helping several go to college.

An animal lover, he was a longtime supporter of the Humane Society of Greater Miami Adopt-a-Pet.

Nat Rosoff learned the building trades from his father, who arrived in New York in 1894 at 12 and worked his way up from barely-literate newsboy to business tycoon, philanthropist and Tammany Hall insider.

He sent his two sons to boarding school as small children. Nat attended Peekskill Military Academy, Connecticut's Milford Prep and the University of Pennsylvania's Wharton School, under its ``Jewish quota.''

At 18, Nat accompanied his father to the Soviet Union, where Sam consulted on the subway system. During the trip, in 1928, the Rosoffs, father and son, were met at the Polish/Russian border by what had been the Czar's private train, which served as their lodging.

On his return to the United States through Paris, Nat stayed at the swanky George V Hotel on opening weekend.

By then, he had seen heavyweight champ Gene Tunney defeat Jack Dempsey twice.

STEAMSHIP LINE

In 1935, deep into the Great Depression, Sam bought the bankrupt Hudson River Navigation Corp.'s steamship line and put Nat in charge. Their elegantly-appointed sidewheelers plied a Manhattan-to-Albany ``night line'' route and ferried tourists to the 1939-1940 World's Fair in Queens.

At the time, they also owned King's Beer, the first New York beer sold in cans. Family lore has it that Nat was once kidnapped and held for ransom after his father sent him to collect on a brewery-related account.

Nat met Gladyce in 1930 through his friend John Schubert, the famed Broadway producer/director. Her nephew, Harry Richardson of Atlanta, said she had been a chorus girl who advanced to secondary speaking roles.

They married a decade later.

In 1942, Nat and Sam, who had constructed barracks for Panama Canal workers, won a $45.7 million contract to build a set of locks on the waterway, but the U.S. government canceled the contract after entering World War II.

FAMOUS BUNK MATE

Cousin Stephen Rosoff of Ann Arbor, Mich., said that during the war, Nat was stationed on one of the Marshall Islands as a communications officer. He was discharged from the Marines as a lieutenant colonel.