Princess Diana is no stranger to an iconic dress, and a midnight blue velvet Victor Edelstein dress she wore 40 years ago this week is a standout among standouts.

The Princess of Wales famously wore the gown to dance with actor John Travolta at the White House on November 9, 1985; as such, the dress became known as “the Travolta dress” afterwards. It features an off-the-shoulder neckline and V-shaped bust, and the bottom of the gown features an Edwardian-inspired mermaid shape. She paired the dress with a stunning sapphire and diamond choker with seven strands of pearls.

Diana—a trained dancer—and Travolta spun around the dance floor for 15 minutes, and in addition to the dress becoming one of her most well-known sartorial choices, their dance also went down as one of the hall of fame moments in Diana’s far-too-short life.

“She was influenced by the cinema and the arts and she was also a very capable dancer—she had wanted to be a ballet dancer as a young girl,” Eleri Lynn, curator of a fashion exhibit at Diana’s former home of Kensington Palace, told People. “So this was really a meeting of her interest in cinema and her love of dance—to be dancing with John Travolta. The dress is a real masterpiece.”

Somehow, Lynn added, the dress is even more magical in person than in photos. “It looks so classical,” she said. “The design is fantastic. You only see the detail close-up. Photos do not do this dress justice.”

“If she had been wearing any other evening dress, it might not have looked so good,” Lynn added. “But that twirling velvet that swirled up as she danced across the floor really made it.”

Diana specifically requested the midnight blue Victor Edelstein gown be made after seeing a burgundy version at Edelstein’s studio; after fittings in Diana’s private apartment in Kensington Palace, Peoplereported she was so pleased with the final result that she rushed to show it to Charles, who told her she looked “wonderful.”

The dress became one of Diana’s most-worn in public, wearing it up to eight times to events such as the 1988 London premiere of Wall Street (where she met actor Michael Douglas), to a banquet in former West Germany, in a portrait in the early 1990s, and in another portrait sitting in 1997—the same year she died at just 36 years old.

The Independent called the Victor Edelstein gown one of Diana’s favorites—hence why she wore it many other times throughout her royal life. Just prior to her death in 1997, she auctioned the dress off as part of a sale to raise money for AIDS charities, with the gown selling for around $131,000 to a Florida native named Maureen Dunkel. The gown sold again in March 2013 for $315,000 to a British man “as a gift to cheer up his wife.” It went on sale again in 2019, but it failed to sell at auction; it was later sold post-auction to Historic Royal Palaces for about $290,000, where it joined the Royal Ceremonial Dress Collection.

“By my count, [it] makes it the dress she wore most,” Lynn, who is curator of the Royal Ceremonial Dress collection, told People. “It was clearly a favorite of hers.”

“It stands the test of time and doesn’t date like some of her other early ‘80s looks,” she added. “The dress marks a turning point in her fashion story, where the incredible New Romantic frills and ruffles gave way to a timeless, classic silhouette. And the number of times she wore it is a testament to that. You could wear it today and still be the best dressed

Diana and her husband Prince Charles were the guests of honor at the intimate 80-person dinner, hosted by U.S. President Ronald Reagan and First Lady Nancy Reagan. At one point, Mrs. Reagan asked Travolta if he would dance with the princess, and the moment became what Travolta later described as “storybook.”

“My heart started racing as I tapped her on the shoulder,” he told Inside Edition. “She turned with a bashful dip and said yes.”

Diana and Travolta’s turn on the dance floor was almost interrupted by another handsome actor in attendance—Tom Selleck, who was asked to cut in because of fears that if Diana and Travolta continued to dance, rumors about them would begin to swirl. After being asked by a female partygoer to cut in, Selleck wrote in his memoir You Never Know that he responded, “I’m not cutting in on John Travolta!” in what Selleck called “probably in too loud a voice.”

“She was not pleased,” Selleck added.

Selleck later told Town & Country of Diana, “She was very gracious and obviously had learned the skill of dealing with people and relaxing. It was certainly memorable.”

It was certainly memorable for Travolta, who told Dutch television station Één that he would “never forget it”: “I didn’t know or expect to dance with Lady Diana, and it was the president’s wife Nancy Reagan that said, ‘It is her wish,’” he said. “At midnight, I had to tap her on her shoulder, and I had to say, ‘Would you care to dance?’ She turned around and dipped her head in that Lady Diana way, and we were off for 15 minutes dancing.”

“I’m so honored that I was able to experience this, and I know for a fact that it was her highlight of being in the United States—it was her favorite moment,” Travolta continued. “So I feel I made her life better, she made my life better, and I’m very sorry that she’s not here.”

He later called the experience “one of the highlights of my life” in a 2016 appearance on Good Morning America and told Esquire Mexico that it felt like a “fairytale.”

“Think of the setting,” Travolta said. “We were at the White House. It’s midnight. The stage is like a dream. I approach her, touch her elbow, invite her to dance. She spins around and gives me that captivating smile, just a little sad, and accepts my invitation. And there we were, dancing together as if it were a fairytale.” He added, “Who could ever imagine something like that would happen to them someday? I was smart enough to stamp it in my memory as a very special, magical moment.”