“IT HAS THE spirit of a loft,” says the interior designer Martin Brûlé, surveying the apartment that inhabits an entire floor of the Sherry-Netherland, the 38-story Jazz Age Fifth Avenue co-op and hotel overlooking Central Park at 59th Street. “The stereotype of a New York loft is that it’s downtown with this artsy feeling, mismatched furniture. Well, this space has all those elements. It’s just a completely dreamy version of that.”

The Montreal-born Brûlé, 38, was commissioned to do the apartment in 2021, a few years after he opened his namesake New York office, by a Latin American-born client with a family of five who works in a rarefied corner of the international jewelry business. Brûlé has since transformed the 11,000 square feet, which once housed the hotel’s barbershop, gym and several offices, into a wildly imaginative and distinctively uptown version of open-plan living. With vast spaces separated mainly by three monumental sets of custom-forged, nickel-plated steel pocket doors, its free-flowing layout is arrayed with finely crafted 18th- and 19th-century European antiques, Modernist furniture from the 1930s and ’40s and a vivid pastiche of intensely colored velvets, silks and satins. The heart of the space is an airy, sophisticated sitting room that connects on the south side to a dining room suggestive of decadent late night suppers in postwar Paris, and an industrial-inflected kitchen. A sensuous lounge and screening room lead to a celestial primary suite and an adjoining boudoir on the north side.

For Brûlé, who is known for subdued tones and disciplined geometries, invoking a TriBeCa loft within an iconic neo-Gothic edifice and outfitting it in a fever dream of color, texture and opulent fabrics was a change of direction. The client, with whom he traveled to galleries and antiques shops in France and Italy, wanted the furnishings to elicit “happy and bright” feelings — and to be exquisitely wrought. “I was open to do anything in the world,” Brûlé says.

One of his inspirations for the décor was a group of socialites and aesthetes who lived in Paris after World War II, among them the Cuban sugar heir and designer Emilio Terry and the Chilean collector Arturo Lopez-Willshaw, whose stylish younger lover, the Baron de Redé, restored the Baroque-era Hôtel Lambert on the Île Saint-Louis and later helped manage money for the Rolling Stones. They were omnivorous and unconcerned with propriety — or the appearance of restraint. “There was a return to lavish living,” says the designer. “They were trying to recreate 18th- and 19th-century excess. It was less about refinement and more about grandeur.”