There’s an old Irish pub in Manhattan’s financial district, Jim Brady’s, that closed at the start of the pandemic and has been sitting empty ever since. The stockbrokers and construction workers who once drank there now walk past with indifference.

But peer through the sooty windows and you’ll see a relic of glamorous midcentury New York — a mahogany bar adorned with floral carvings that is said to have belonged to the Stork Club, a fabled nightspot whose customers included Grace Kelly, Humphrey Bogart, Elizabeth Taylor, J. Edgar Hoover, Marilyn Monroe and members of the Roosevelt and Kennedy families.

Those who made it past the gold-chained entrance stepped into a place where the cult of modern American celebrity was arguably born. From Table 50, the journalist Walter Winchell gathered materials for his nationally syndicated gossip column and radio show, ensuring that Stork Club’s legend loomed large.

The mahogany bar at Jim Brady’s, which improbably ended up there in the 1970s, now collects dust in obscurity.

“It’s still in there, the original Stork Club bar,” Paul Quinn, the former owner of Jim Brady’s, said in an interview. “I was there when the pub opened, and it became known to our regulars that we had a piece of New York history.

“The bar had been in storage for years,” he continued, “and the founders of Jim Brady’s purchased it and brought it down piece by piece.”

Mr. Quinn, who started working at Jim Brady’s as a bartender almost 50 years ago, said he would have taken the bar with him when his tavern went out of business, but his lease stipulated that the fixtures had to remain on the premises.

“I took pride in taking care of it all those years,” he said. “Once a man called me and asked, ‘Is it true?’ I told him, ‘Yeah, it is.’ So he came down to look at it. He touched the wood and felt the bar. I could tell it meant a lot to him. He’d gone to the Stork long ago.”

Today the Stork Club’s lore is of interest mainly to New York history buffs, but during its reign, what happened in the Cub Room — its windowless inner sanctum — riveted the American public.

Grace Kelly and Prince Rainier III of Monaco mingled at the Stork Club just before news of their engagement circulated the globe. Ernest Hemingway got into a brawl there with the warden of Sing Sing. John F. Kennedy brought dates there — Jacqueline Bouvier and, later, Marilyn Monroe.

The fantasia was orchestrated by the club’s owner, Sherman Billingsley, a former bootlegger from rural Oklahoma who reinvented himself as a nightlife impresario. He wore gold cuff links and watches, uttered regionalisms like “golly” in conversation with stars and used secret hand signals to telegraph messages to his staff that ranged from “Bring a bottle of Champagne” to “Not Important People.”

“I have seen mothers steal their daughters’ boyfriends and marry them,” Mr. Billingsley wrote in an unpublished memoir. “I have seen girls steal their sisters’ boyfriends and marry them. In one case the loser went insane. I know one father that was familiar with his son’s wife. These were all high-society folks.”

Founded in 1929, and closed in 1965, the Stork Club’s three successive Midtown Manhattan addresses rode out the Great Depression, World War II, the arrival of Elvis and the start of the Vietnam War.

Its first iteration was a speakeasy that Mr. Billingsley operated with mobsters before it was smashed up and shut down by federal agents enforcing Prohibition laws. Its second location had the beginnings of his opulent vision, drawing fans like Winchell and the underworld boss Frank Costello. This iteration survived past Prohibition’s end in 1933, leading Mr. Billingsley to move the Stork Club to its final and most famed address, 3 East 53rd Street.

The first location is now a Greek restaurant, the second is an office building, and the third was demolished to make way for the pocket-size Paley Park.

The bar that ended up at Jim Brady’s is said to have come from an early Stork Club location. For decades, it was admired mostly by its happy-hour regulars. A replica of a vintage Stork Club menu — featuring dishes like green turtle soup for $1.50 and stuffed Cornish hen à la Walter Winchell for $5.75 — sat near the Jim Brady’s cash register.

The bar’s presence at Jim Brady’s was noted in articles published in Time Out and Shecky’s Bar, Club & Lounge Guide that were displayed in its window. It was also mentioned in New York history books like William B. Helmreich’s “The Manhattan Nobody Knows.” A financial district walking tour would stop in to gawk at the bar on weekends. Still taped to a wall inside the pub is an old flier with a picture of Joe DiMaggio and Marilyn Monroe drinking at the nightspot. It notes: “Did you know that Jim Brady’s is home to the World Famous Stork Club Bar?”

Mr. Billingsley’s last living child, Shermane, 77, has been a custodian of the Stork Club’s legacy since her father died in 1966, and she visited Jim Brady’s long ago to see the bar for herself. “The story about this bar ending up at this pub was always circulating, so I went down to take a look, and what I saw felt right to me,” she recalled. “I sat down for dinner in a booth and remained anonymous until I left. Then I told them who I was.”

Reminiscing about her visits to the Stork Club as a teenager, she said: “It was something I can’t honestly compare to another place today. It had glamour and an intellectual fervor to it. I’d sit with my dad and he might say, ‘Shermane, I want you to meet Jackie Gleason.’ Or it was Cary Grant. Or Yul Brynner or one of the Hearsts.”

Earlier this month, Ms. Billingsley visited Jim Brady’s again with a reporter from The New York Times, and she brought along her younger son and a cousin, who once danced as a teenager at her father’s club. A petite and elegant woman, Ms. Billingsley arrived wearing sunglasses, Chanel ballet flats and a gold ring given to her by her father that depicts the club’s mascot, a stork with a monocle and a top hat.

Studying the bar, she considered an ornamental carving that read, “J.B.” The founders of Jim Brady’s were told when they acquired the bar that the initials were a dedication to Mr. Billingsley’s daughter, Jacqueline.

“She was the first daughter,” Ms. Billingsley said. “She was incredibly important to him. This isn’t surprising to me.”

Then she grew somber.

“I was there when the Stork Club closed,” she said. “Everyone said it was the unions that caused its demise. But it was James Dean. It was black boots and jeans. It was the arrival of the new world.”

By the late 1950s, the Stork Club began to erode into irrelevance. Several incidents hastened its decline.

Mr. Billingsley’s vociferous anti-union stance led to a bitter yearslong strike and the loss of longtime staff members. The rising popularity of TV was luring even the most social of socialites to stay in and watch “I Love Lucy” and “Gunsmoke” rather than go out on the town. And a flashy new era of gambling-based nightlife was taking off in Las Vegas, Miami and Havana.

The club’s unraveling can also be traced to an October night in 1951, when the Black singer, dancer and activist Josephine Baker said she experienced discrimination there.

Ms. Baker, who rose to stardom in the music halls and cabarets of Paris, went in that evening with friends and sat down at a table in the Cub Room. After ordering, Ms. Baker said, she and her dining companions were ignored for an hour. She was eventually informed that the kitchen was out of the steak and crab cocktails she had asked for.

Ms. Baker headed to a phone booth to report the indignity to her lawyer and a deputy police commissioner. As she settled back into her seat, the club learned of these calls, and a waiter rushed out her steak. Ms. Baker refused to eat it.

The incident dominated the city’s headlines for days. The N.A.A.C.P. picketed the club, and protesters carried signs reading “Famous Nite Spot Just a White Spot.” Ms. Baker sparred in the press with Mr. Winchell, accusing him of not coming to her aid in the Cub Room. He retaliated by exposing rumors of her communist sympathies to the F.B.I., resulting in the cancellation of her upcoming shows, the revocation of her visa and her return to France.

In the aftermath, some of the Stork Club’s patrons began distancing themselves from the club, and it staggered toward the decade of revolutionary change ahead. By the end, it was promoting itself with a hamburger and fries deal for $1.99, and the live band was replaced by a sound system. A year to the day that his club closed, Mr. Billingsley died of a heart attack.

“By the time it closed, it wasn’t the famous Stork Club anymore,” said Ralph Blumenthal, a former Times reporter and the author of “Stork Club: America’s Most Famous Nightspot and the Lost World of Café Society.” “But it was also the end of a whole era. It wasn’t just the Stork, it was places like El Morocco and the Colony. The way people wanted to go out had changed.”

“It’s an interesting fact that pieces of New York have a life after death,” he said of the bar at Jim Brady’s. “A bar encapsulates the Stork Club’s history, in a way, because everything that happened there happened around the alcohol.”

The pub’s founders bought the Stork Club bar at an auction in the mid-1970s, after it had been languishing in storage for years, according to five former Jim Brady’s employees and associates. These Irish restaurateurs — Desmond Crofton, Terry O’Neill and Gerry Toner — ran an empire of Manhattan pubs that included the Abbey Tavern and the Green Derby.

When opening Jim Brady’s, they enlisted two other founding business partners: another restaurateur, Roy Barnard, and the noted Dublin-born balladeer Michael Jesse Owens, who performed tunes like “Whiskey in a Jar” beside the relic at night.

“We were proud to have the Stork bar,” said Mr. Owens, who, at age 87, is the group’s last living member. “But to a lot of us Irish, it was also just a bar. Still, it’s a pity to hear it’s just collecting dust now.”

At Jim Brady’s, the ancient bar became a gathering spot for a different New York. Peter O’Toole nursed pints of Guinness there, and the newspaper columnist Jimmy Breslin drank at the bar once as he killed time waiting to be contacted by David Berkowitz, the murderer known as Son of Sam.

As the decades passed, and Jim Brady’s became a financial district institution, the old bar serviced Super Bowl parties and rowdy brunches. After the terrorist attacks of Sept. 11, a wall of tribute to regulars who died during them was installed near it.

In 2020, when the pandemic seized New York, Jim Brady’s closed because of a rent hike that Mr. Quinn said he couldn’t afford. The pub’s final evening of service was on St. Patrick’s Day. Its staff gave out corned beef to longtime customers and then gathered for a drink by the bar before hitting out the lights. Earlier this year, briefly, the vacated tavern saw life again when it was used as a Covid-19 testing center. Visitors had swabs shoved up their nostrils beside a hunk of wood that was around during the polio epidemic.

“I considered it an honor to serve drinks on it,” said Joe O’Dea, a former Jim Brady’s bartender. “I don’t know if I have some profound thought on it still being in there, though. Maybe it teaches you not to be sentimental about things in New York.”

“I wonder what will become of it now,” Mr. Quinn said last week, peering through his old pub’s windows. “It’ll probably end up in some dumpster truck.”

As it happens, the bar’s fate may be at hand.

A.M. Property, the real estate group that represents the building that housed Jim Brady’s, 75 Maiden Lane, is a family-run company that owns two other office buildings in the financial district. Its president, Paul Wasserman, said in an interview that an elementary school is interested in leasing the space.

“It might not be around much longer,” he said. “I don’t think a school will have much use for a bar.”

“I didn’t know the bar was from the Stork Club, and I’m of the generation that knows what the Stork Club once was,” Mr. Wasserman continued. “Still, I’m not nostalgic about this bar in any shape or form. Time marches on in New York. The only constant here is change.”

“Today is no different,” he added. “And tomorrow won’t be either.”