The six-and-a-half-foot-tall Mr. Tune, a nine-time Tony Award–winning actor and dancer, paid $1.29 million for the tower apartment at 400 East 52nd Street, called the Southgate.

It had belonged to the late interior designer Christopher Gallo.

A year and half ago, Mr. Tune first visited the building to see its penthouse. “The ceilings weren’t high enough,” he said. “I need head room, of course, obviously.” But he spotted a narrow passageway: “And I do not have a pioneering spirit, but I took off the chain and eked up the little narrow staircase. And suddenly I saw this place; I was like a peeping Tom.”

But the tower apartment he discovered wasn’t on the market, so he told a neighborhood florist (named Zeze—really!) to keep his eye on it. A year later, Zeze phoned Coldwell Banker Hunt Kennedy broker Patricia Scott Berkule to say the apartment was available—and that she should get Mr. Tune to see it.

Even though Mr. Gallo’s estate already had another potential buyer, Ms. Berkule and her partner, Mary Nealie, arranged for Mr. Tune to visit the one-bedroom, 750-square-foot apartment.

“It’s magic beyond belief,” he said. The place has a wrap terrace and cracked walls: “Absolutely romantic, in the Roman sense of the word. I’ve fallen in love with the walls in Rome—they don’t paint them, they let them live. There’s history in these walls, so I’m not touching them.

“I don’t want many things—I honestly don’t. But I looked at this place and said, ‘I want this place.’ And—ahem—I have it.”