It was sometime in the fall of 2013 when Frank Farella, the general manager of the Seagram Building, the 38-story Ludwig Mies van der Rohe modernist masterpiece on Park Avenue, first suspected that there might be a problem with the back wall of the building’s lobby. Farella, according to court documents, was on a routine inspection when he noticed the “buckling” travertine wall panels in the passage between the two dining rooms of the famed Four Seasons restaurant. The corridor is known as Picasso Alley because a towering, 19-by-20-foot work by Picasso—the largest Picasso canvas in the United States—has hung on that wall since 1959, when the restaurant, which was designed by the American architect Philip Johnson, opened. Behind the Picasso, on the other side of the wall, Farella said in an affidavit, was the Four Seasons’ two-story kitchen, the source of his concern, that a “potentially serious” steam leak could be creating a situation where the wall was “rotting from the inside.” Farella immediately conveyed this news to the man who owns the Seagram Building, the real-estate developer and contemporary-art collector Aby Rosen. In early November 2013, Rosen contacted the owner of the Picasso—the New York Landmarks Conservancy. As its president, Peg Breen, said in her affidavit, Rosen informed her that he was going to remove the Picasso from the Four Seasons because of concerns that it “was being damaged by a leaking steam pipe and potential issues with the stability of the wall.”

Within days, Breen sent a conservator to examine the Picasso. Her report was unsettling. A stage curtain painted in 1919 for Sergey Diaghilev’s legendary Ballets Russes, Le Tricorne, she concluded, was simply too fragile to be moved. The paint and the fabric, the conservator said, were at risk of cracking—“like a potato chip,” another expert said. Removing the historic, 94-year-old Picasso curtain, according to the conservator, “will more than likely result in irreparable damage.” Soon after, Breen received a report from an engineer hired by the Landmarks Conservancy. After inspecting the area around the Picasso, he “confirmed,” Breen said, that there was “no evidence of stress or recent movement in the Travertine Wall,” and “that there was no steam pipe, let alone a leaking steam pipe, in the vicinity of the Picasso Curtain.”

And so began the battle over the Picasso. It has involved art and architecture critics and historians, engineers and conservators, indeed, much of the New York art world—many calling for the Picasso to remain in place. In February, the conflict became fevered when the Landmarks Conservancy got wind of Rosen’s plans to remove the Picasso in the dead of night—at three A.M. on February 9. It filed for a restraining order against Rosen’s real-estate company to enjoin him from moving the curtain. The accusations and the rumors flew. One rumor was as much of a shock to some of New York’s players as the possible removal of the Picasso: that this was the first step in Rosen’s plan to shut down the Four Seasons.

With its soaring ceilings, white marble pool, and magnificent dining rooms, the Four Seasons is one of the most elegant restaurants in the world. It stands today, according to some critics, as the first modern luxury restaurant. It has also been known as “absolute ground zero for power lunching,” as Vanity Fair referred to it in 1999. It is where President Kennedy’s 45th-birthday dinner was held in May 1962—just before Marilyn Monroe serenaded him with “Happy Birthday, Mr. President” at Madison Square Garden; where on just about any day the list of diners included the city’s best known—Brooke Astor, Jacqueline Onassis, the mayor, the governor, the heads of major investment banks and publishing houses. Its service was and is impeccable—in April, the New York Post noted that the restaurant’s staff scurried to fill Warren Buffett’s order of a steak, Cherry Coke, and dessert from Dairy Queen. Its clientele is devoted. “There is no place like it,” says one financier. In the midst of all the power-brokering, the architecture and space lend it “a quality of repose.”