I had read about The Four Seasons in magazines like Esquire and Time and Life, but I hadn't seen photographs of it, and it wasn't at all what I expected. I suppose it was the stark modernism of the rooms that threw me. I thought they would be clubbier, more like the Plaza's Oak Room in appearance and feel. By the second or third visit, I came to appreciate the thought that went into the design. Like others before me, I learned to understand the elements that Mies van der Rohe and Philip Johnson had put into the restaurant, and even more importantly, the elements they left out. One thing I always marveled at—and I have no idea whether this was planned or not—was that if you put a water glass on the table, the lights from the ceiling sparkled around the glass and traveled perfectly with it if you slid it across the table.

To look around the room was an education in who the defining New York powers were at any given point. You'd ask who this person was, and someone would whisper, “Oh, that's John Loeb. The investment banker.” One of the first times I clapped eyes on Barry Diller was at The Four Seasons. And if you'd read about some of these people your whole life, seeing them in the flesh—at a restaurant, eating a few tables away—well, that was New York. I loved seeing Brooke Astor having lunch with Philip Johnson or David Rockefeller. At one point or another every character in the big footprint of the last half of the last century ate there. Si Newhouse, a pillar of comfortable officewear, used to keep a jacket and tie in his office just for lunches at The Four Seasons.

Julian Niccolini and Alex von Bidder, the restaurant's two managing partners, brought a lot to the table. First of all, they were there every day, which was key. Restaurants—the big successful ones—are at heart, proprietorships. And it is essential that the proprietors are in the house. Also as much as restaurants are a form of impromptu theater, this works only when there are talented directors around to police the traffic. The good ones like Julian and Alex run the show with apparent ease. They are going to go off and create magic elsewhere, but it will be a different magic, with a whole new set of tricks. The Four Seasons was, in the language of Las Vegas, “The Big Room”, and it will be a very different animal going forward. The restaurant came into this world almost a decade before the Concorde—another marvel of clean line and love of the future—and outlasted it by a decade. For more than half a century, The Four Seasons was a shimmering miracle of light, murmur, and quiet power. And now it's gone and the void will be felt.

Johnson, ever conscious of what he called the processional aspect of architecture (he once wrote an essay in which he said that buildings could only be experienced by moving through them) unveiled the restaurant's treasures gradually, almost cinematically. You entered The Four Seasons not into a tiny vestibule, but through a wide, low-ceilinged, travertine lobby on the ground floor, the luxury of which was but a hint of what was to come. A wide staircase at the far end of the lobby beckoned you upstairs; as you turned on the staircase landing, the space that had been low began to soar, opening up to reveal the first of the two dining rooms, the Grill Room, with a large, square bar, wall paneling of French walnut, a Richard Lippold sculpture of anodized metal rods, and high windows with chains of aluminum, brass and copper as curtains. Along the far wall, nestled in front of a raised balcony, were five wide banquettes, two rectangular and three semicircular, with tufted seating designed by Johnson; they were the favored seats at the restaurant's famous “power lunch,” and Johnson himself occupied Table 32, the banquette in the southeast corner, almost every day for more than forty years, hosting clients when he had to, more often lunching with colleagues and younger architects whose work had interested him. His table, the architectural historian Vincent Scully once noted, was really a long-running architectural seminar, set against the backdrop of his own work.

Johnson may have conceived of The Four Seasons as a “gesamtkunstwerk”— a total work of art — but his desire for consistency did not mean he saw the project as his design alone. Johnson used Mies van der Rohe's Brno chairs, upholstered in a midnight blue fabric manufactured especially for The Four Seasons, as dining chairs around the freestanding tables, and he and Seagram Corporation, which paid most of the $4.5-million cost of building the restaurant—high today and extraordinary in 1957, when the project started—commissioned the industrial designer Garth Huxtable and his wife, the writer and critic Ada Louise Huxtable, to design special glassware and silver tableware especially for the restaurant. The interior designer William Pahlmann played a role, and the detail-obsessed Joseph Baum, the executive of Restaurant Associates, the management company that initially ran the restaurant, was involved at every step of the way. Baum more or less invented the theme restaurant, and at The Four Seasons, you could say that the theme was his most ambitious, if hardest to define: not a play on some ethnic cuisine but the marriage of high modernism and old-fashioned elegance.

Space was not the least of the luxuries that The Four Seasons offered: as New York became more and more crowded, more and more noisy, The Four Seasons was the place where you could retreat into a kind of monumental softness, where conversations would never be overheard, and where every occupant of every table could feel as if he or she had escaped somehow from the intensity of the city. At the same time, of course, it was the most New York of places, even as it held the urban frenzy at bay. Not only was the clientele a parade of boldface names, especially at lunch in the Grill Room; you could walk into The Four Seasons when the place was empty and it still conveyed a sophistication, an aura, that seemed to bespeak the city at its most cosmopolitan.

Still, for all that the restaurant's celebrated clientele contributed to the feeling that The Four Seasons could have been nowhere else, it was really the architecture itself, and the art within it, that made it what it was. Lippold's sculpture (which will remain in the Seagram Building since it is covered by the restaurant's interior landmark designation) could not have been anywhere else: the sculptor created it not just to decorate the generous space but, in effect, to work with the room to create the illusion of more intimacy around the bar. The piece has a second section, a set of metal rods diagonally across the room, over the balcony, which exists in gentle counterpoint to the main section over the bar. Here, sculpture and architecture work in perfect harmony.

Johnson, with Seagram Corporation's assent, also commissioned the artist Mark Rothko to paint a set of murals for a private dining room adjacent to the restaurant's main dining room, the Pool Room. The Rothko murals were never installed; the artist made three different sets, and ultimately resigned the commission, deciding that he was uncomfortable having his work surround people who were eating, rather than museum-goers who could contemplate it without distraction. Over the years there were numerous other works of art installed in the private dining room, including a large mural by James Rosenquist that hung there for several years. The Pool Room itself had no art: here, the enormous, high space was interrupted neither by an entry staircase nor a bar, and it was given architectural definition by a marble pool in its center, and by a wider expanse of the same high windows and shimmering curtains as in the Grill Room. Four trees, changed to note the passage of the seasons, stood at the corners of the pool: the vertical presence of their trunks, along with the horizontal surface of the glimmering water and marble, gave the space its demarcation and its rhythm.

The restaurant's most celebrated work of art was removed in late 2014: Le Tricorne, a 19 by 20-foot painted curtain created by Pablo Picasso in 1919 for the Ballet Russe production of Diaghilev's ballet. It was purchased in 1958 by Phyllis Lambert, an architect and the daughter of Samuel Bronfman, the head of the Seagram corporation, who had convinced her father to hire Mies van der Rohe and Philip Johnson to design his company's headquarters. Lambert, who was also involved in efforts, ultimately unsuccessful, to commission works for the restaurant from the sculptor Brancusi and the artist Joan Miró, was a key figure in the history both of the building and of the restaurant—perhaps the key figure, since it was she who persuaded her father to abandon an earlier plan to build a banal commercial skyscraper and to put up a masterpiece instead. Lambert proposed that the Picasso hang in the long travertine corridor that connected the Grill Room and the Pool Room, where it would command its own monumental, if narrow, space, provide a meaningful moment to punctuate the promenade from one dining room to the next, and be visible through a glass wall to the building's main lobby, making it, in effect, an icon of the entire building and not just of the restaurant.

The decision by the present owner of the Seagram Building, the restaurant's landlord, to order the curtain removed in 2014 set in motion the series of events that would lead, in 2016, to the departure of The Four Seasons from the space that had been designed by Mies and Johnson for it, and to the decision to create a new Four Seasons restaurant elsewhere in midtown Manhattan. That restaurant will be altogether different: by July of 2016 The Four Seasons as envisioned by Philip Johnson will have had a 57-year run at the Seagram Building, which is extraordinary longevity by restaurant standards, and Alex von Bidder and Julian Niccolini, who have owned and run The Four Seasons since 1994, along with the Bronfman family, which retains an interest in the restaurant, invited the gifted architect Isay Weinfeld from Sao Paulo, Brazil, to New York to create a new Four Seasons restaurant that they want to make as important a part of the architecture of the 21st century as the original Four Seasons has been to that of the 20th. Von Bidder and Niccolini know that they cannot bring the Seagram Building with them, and the decision to sell the restaurant's furniture and table settings is a way of acknowledging that the masterwork that the current restaurant represents, the idea of the original Four Seasons, has come to an end. Although the restaurant's physical space will remain largely intact owing to its status as a New York City landmark, small pieces of the original Four Seasons will be scattered far and wide, each one a reminder of the high ambition, the idealism, and the serene beauty of one of the most cherished modernist designs of all time.