PARIS — Le Castiglione, the retro-glamorous cafe with a long, marble bar, red velvet banquettes and warm, flattering lighting, drew its red curtains for the last time early Sunday morning.

For more than 30 years, Le Casti, as it is known, had attracted well-turned-out habitués from the worlds of fashion, film and design. In the morning, it was a favorite among locals and employees from nearby boutiques who come to read the paper over a coffee, and maybe have a cigarette on the terrace before work. At noon, it became a discreet power-lunch spot for magazine editors, designers and fashion publicists, interspersed with tourists quaffing Champagne over a salade niçoise.

After hours, the music turned up slightly for the aperitif crowd, a mash-up of off-duty A-listers, fashion insiders and visitors who returned again and again for the 37-euro “Casti burger” made famous in a 2002 article by Cathy Horyn, then The New York Times’s fashion critic. After that article, American visitors began dropping by just to see whether Tea Time, the resident English springer spaniel, was really there. (He usually was.)

If Le Castiglione’s wood-paneled and mirrored walls could talk, they’d whisper about the comings and goings that made this haunt a must. Like the time the Rolling Stones turned up rowdy after midnight, just as the kitchen was closing, demanding dinner. Or how the longtime Vogue eminence André Leon Talley would breeze in from the Ritz or Le Meurice for breakfast wearing a feather boa, returning at night with a glittery entourage.

Or how Kate Moss would dine quietly in a corner while the staff kept paparazzi at bay outside. Or, recalled Jean-Christophe Affolter, the restaurant’s general manager, how a tiff between an A-list American actress and her husband got so fraught upstairs that the entire waitstaff decided to sit it out downstairs.

Le Castiglione’s closing doesn’t just change the fashion landscape; it transforms the face of Paris. A pillar of the Place Vendôme neighborhood and arguably its best, and most photogenic, cafe, it is the last storefront to shutter on the ground floor of a building that was originally part of an 18th-century convent and sits on the Rue St. Honoré just opposite Louis Vuitton.

As recently as Thanksgiving, its immediate neighbors included the chocolatier Pierre Marcolini, the hairdresser Alexandre de Paris and, under the nearby arcades on the Rue de Castiglione, perfume shops for Annick Goutal and the jewelry designer JAR. By Christmas, a real estate developer had begun renovations that will reconfigure a vast retail space that, once finished, will be home to a Gucci flagship with a restaurant.

For Fabrice Couet, the owner of Le Castiglione, closing signals the end of a chapter in his life that began in 1990, when Mr. Couet, then 24, took over the lease for a floundering café américain — the kind that serves drinks and not much worthwhile food — alongside his father, Pierre.

“It’s a little bizarre, because my daughters used to go to school in the neighborhood, and they’d come for lunch,” Mr. Couet said. “We’ve watched the entire neighborhood change into the Avenue Montaigne,” he added, referring to the touristy Right Bank shopping destination. When he arrived, his was one of six old-fashioned Parisian cafes that dotted the section from the Rue Royale to the Rue de Castiglione. As of Sunday, there were none.

One of Le Castiglione’s earliest loyalists was the ABC News correspondent Deborah Roberts, who recalled discovering the place while honeymooning with her husband, Al Roker, 27 years ago.

“We stayed at Le Crillon and stumbled across this very cool bistro,” Ms. Roberts said in a phone interview. “We stopped in for coffee and then returned again, and it just became a part of us.” Now that the couple’s daughter lives in Paris, the family tradition had carried on.

When she learned of the closing, “it felt like a gut punch,” Ms. Roberts said. “Le Castiglione is as much a part of our Paris experience as anything is, and I just assumed I would be going there, with my family or with my girlfriends, just to breathe the air of Paris, have Champagne and eat frites.”

Business was lean in the early years. At the time of the first Gulf War, in 1991, the neighborhood was filled with small, independent businesses, like galleries, a tailor and specialized shops selling toy soldiers or jewelry. When tourists stayed home, the cafe’s clientele was mainly lawyers, bankers and insurance executives who worked in and around the Place Vendôme. Luxury shopping then was concentrated on the Faubourg St. Honoré, west of the Rue Royale, and older business owners around the Place Vendôme struggled to sell their spaces.

Then, with the opening of the Hotel Costes, in 1995, followed by the concept store Colette, a few blocks down, in 1997, and the arrival of Goyard next door the year after that, the area was reborn. Mr. Couet kept Le Castiglione an Old World-style cafe, run with two longtime employees, Mr. Affolter and Augustin Martinez, a manager; occasional help from his life partner, Claudia Castro, a Brazilian-born American; and the company of his spaniel, Garry, a direct descendant of Tea Time.

For some clients, Mr. Couet and Ms. Castro have become like family. No longer having Le Castiglione, many said, will transform their way of living and working.

“It’s a monument,” said Yasmin Kayser, a former market editor for French Vogue who is now the editorial business director at the fashion magazine Mixte. “The history’s different, but it’s almost as if the Deux Magots was closing. For 20 years, it’s been the place where I’ve gone for breakfast, lunch and dinner and met people from the industry. It’s like a little world unto itself.”

For Grégoire Marot, the founder of the boutique public relations firm Favori, a table on the terrace at Le Castiglione was almost an extension of his office, which is next door, one floor above Goyard.

“If I’m not there three times a week, I’m on vacation,” he said. “I’d go for coffee and have this strategic position where you can do your job. Here, there’s the Ritz, and there’s the Castiglione. It’s not like in the U.S., where everything is immediately reborn. It’s the end of something. It’s sad, but c’est la vie.”

Marc Auclert, a jewelry designer who has long lived in the neighborhood and has a shop on the Rue de Castiglione, said that this section of the Right Bank is experiencing the same kind of transformation that rattled St.-Germain-des-Prés a generation ago, when the Drugstore Publicis was converted into a Giorgio Armani boutique and restaurant.

“I’m sure whatever they do here will be beautiful, but it will be another world,” he said.

Mr. Auclert described the morning crowd at Le Castiglione as a little social group of soft connections, people who have known one another for years but don’t necessarily need to talk.

“It’s also the best way to learn who’s just arrived at the Ritz,” he said.

Starting Monday, Mr. Auclert and his fellow regulars will have to choose a new morning headquarters. At the moment, there are few contenders — perhaps Da Rosa Jr. or Maisie Café on the Rue du Mont Thabor, or La Coupe d’Or, a more-or-less traditional cafe that runs more on efficiency than ambience.

In the meantime, as the news spread, Mr. Couet said he had been contacted by clients from all over the world who want to buy a lamp, a bar stool or other memorabilia.

For those with a bit of patience, however, Mr. Couet has been quietly cooking up a new project. In January 2020, he bought the Café des Tuileries, on the corner of the Rue de Rivoli and the Rue du 29 Juillet. Like Le Castiglione 30 years ago, the place had seen better days.

On a recent January afternoon, the Café des Tuileries was full, and Mr. Couet’s daughter Carla was serving customers. He is planning to close it for renovations. When it reopens, some of Le Castiglione’s banquettes, now reupholstered in green velvet, as well as tables, dishes, glasses and silverware, will have found a new home opposite the Louvre and its gardens.

While details like dates, work permits and interior décor have yet to be confirmed, one thing is certain: The Casti burger will still be on the menu. That, and Garry will be there, too.