In the lobby of a downtown Manhattan tower, Nathan Berman pauses to admire the marble walls and terrazzo floors. A real estate developer, he has a taste for old-world detail, like the fur lining in his navy overcoat, accented with a ­polka-dot scarf. It’s rush hour in the heart of Wall Street, and Berman’s at its white-hot center, 55 Broad St., former offices of Goldman Sachs Group Inc. But, like many buildings in the age of working from home, this onetime hub of capitalism is largely empty. Many of Berman’s rivals would be discouraged. He’s thrilled.

Berman transforms vacant office buildings into top-of-the-line apartments. At 63, he’s the king of office conversion. From the 23rd floor of 55 Broad, Berman can make out five of his projects in the bright December sunlight. They include 20 Broad, a midcentury modern building that had outlived its usefulness as the onetime headquarters of the New York Stock Exchange. Today, along with apartments, it features a rooftop terrace with views of the harbor, a theater, a yoga studio, a game room and a fitness center. Gazing into the distance, Berman points toward another of his alchemies: a former Tribeca bookbindery where Oscar-winning actor Jennifer Lawrence and pop star Harry Styles have owned homes.