At 73, Bernadette Peters is the epitome of ageless beauty. She still looks as radiant and youthful as she did in the 1980s — and she has the dress to prove it. On Sunday, Broadway's grand leading lady hit the Tony Awards red carpet dressed in one of her own vintage Bob Mackie gowns. And the internet went nuts for it.

"It's not every woman in Hollywood who can step into her 40-year-old dress and have it fit like it was made yesterday," Bob Mackie exclaims over the phone from his California home on the Tuesday after the Awards. "Bernadette is extraordinary."

Peters originally wore the black strapless gown in an October 1983 spread for Orange Coast Magazine, though Mackie can't recall the exact details of when he first designed the dress, which features embroidered gold stars and a tulle trimmed neckline. Even then, though, she was considered ageless. "Her beauty is somewhat historic, a relic of the '20s and '30s," writer Bryon de Arakal says of her in the article.

Peters met Mackie for the first time on the set of The Carol Burnett Show in 1967, where Mackie was in charge of costumes. Since, he's designed numerous gowns for her over her luminous seven-decade career, including the strapless sweetheart dress she wore while accepting her first Tony Award back in 1986, and her wedding dress to the late Michael Wittenberg in 1996.

Preparations for Peters to appear in the dress were made months in advance. Mackie had just finished creating a new concert look for her upcoming engagements ("a wonderful root beer terracotta color that matches her hair") when he asked her assistant to bring in this particular dress to the fitting at Tricorne Costumes in Manhattan. He had reminded Peters that she had not worn it in quite a few years. It had been stored neatly in a box at her New York City home. "Bernadette takes very good care of all of her performing dresses," Mackie explained. The last time she was seen wearing it was in 1997 for the 10th anniversary reunion concert of Into The Woods.

Once Peters tried it on, Mackie explains, all the dress needed was a little needle and thread before hitting the red carpet. "It was just a couple pins here, a pin there. A little fluff there. A couple days later it was ready to wear. It was nothing." They felt this year's Tony Awards would be the perfect place for her to be photographed in it again.

The gown has always been one that Peters thought of fondly. When I asked her which Bob Mackie gown of her's was her favorite on the red carpet for the opening of The Cher Show on Broadway, she replied, "[the] one with a lot of tulle and stars on it."

This particular gown will be featured in Mackie's upcoming book, The Art of Bob Mackie by Frank Vlastnik and Laura Ross. The forward was written by Carol Burnett and the afterward by Cher — two more legends the designer has spent decades dressing. It will be the first comprehensive and authorized showcase of his work and life. The pages are full of hundreds of photos of clients like P!Nk, Liza Minnelli, Beyoncé, RuPaul, and Madonna, and never-before-seen sketches from Mackie's personal collection.

"I've heard people say that when I wear a dress designed by Bob, they like to take bets on whether or not it'll stay up. I have two reasons it will," Peters quips in the book.

Mackie said it was "fun to see her in current pictures" side-by-side with photos from 40 years ago. The look on Peters reminds him of something the actress Lillian Russell from the late 19th century would wear. "She just always looks like from another time. She sort of looks like one of those people with their portrait on the wall," he says.

He adds: "Nothing changes. She stays the same."