Marilyn Monroe made history once more this summer when her personal mementos and rare photos earned more than $11 million at Julien’s Auction’s in Los Angeles — and now fans of Hollywood’s most famous sex symbol will finally learn the story behind her belongings.

The auction was chronicled by the Smithsonian Channel for a special titled “Marilyn Monroe for Sale,” which details her life while following highlights from the sale, including the infamous dress she wore to serenade President Kennedy on his birthday in Madison Square Garden.

The documentary features interviews with biographers, historians and Bob Mackie, costume designer to the stars.

Marilyn Monroe's "Happy Birthday Mr. President" dress. (Smithsonian Channel)

Marilyn Monroe died in 1962 at age 36 from an apparent drug overdose. The three-day auction dedicated to her memorabilia earned $4.8 million alone for the sheer birthday dress, which was purchased by Ripley’s Believe It or Not.

Executive producer Nicolas Kent told Fox News it was exciting to uncover the little-known stories behind the star’s personal possessions for the documentary.

“It was an Aladdin’s cave of unseen, personal material from Marilyn Monroe,” said Kent. “She left her collections to her old acting coach Lee Strasberg … And we’re talking about really intimate things. Notes she wrote to herself on a menu, contracts she signed, prescriptions, the drugs she was taking. Really personal stuff that give an amazing insight into Marilyn’s life. Contrary to the reputation of being a dumb blonde, she was not dumb. In fact, she wasn’t blonde either.”

Marilyn Monroe's makeup and cigarettes. — Smithsonian Channel

Kent added that even though Monroe died over 50 years ago, her memorabilia is hotter than ever.

“In some ways, these items are almost like religious relics,” said Kent. “People just flock to them. These items that you wouldn’t think would have any value actually go for thousands of dollars just because Marilyn owned them. A recipe for stuffing that she liked in 1957 sold for $6,400.”

One of the most sought-after images from the auction were photos from the 1949 “red velvet sessions." Before Monroe became a movie star, she posed nude for photographer Tom Kelley in hopes of making a quick buck during a time when she was struggling to find work as an actress. Monroe was allegedly paid $50 dollars to strip down as long as Kelley's wife was present during the racy shoot.

Marilyn Monroe on the cover of the first issue of Playboy. — Getty

A year after the cash-strapped Monroe posed for the nudes, her acting career began to take off in Hollywood. NPR reported that once Monroe became a star, Hugh Hefner bought the rights to those photos for $500 from a calendar company for his new magazine titled Playboy. The men’s lifestyle publication became a sensation and Monroe never received another dime from the daring snaps.

“The photos make Playboy, but the Hollywood studio is massively embarrassed by this,” said Kent. “They’re basically telling Marilyn to deny and reject those photos… she ignores this advice. She just admits to it. And she does it in such a charming, smart way that instead of suffering from it, she actually becomes more famous, and it really boosts her sex appeal. Monroe stands up to the establishment.

"In the ‘50s and even early ‘60s, America and the world was a much more prudish place. It’s one of the reasons why Marilyn survived as such an iconic figure. Her sex appeal was so pure and unapologetic.”

In her lifetime, Monroe was so sought-after by fans that she even had her own groupies or “the Monroe 6,” a group of teenagers who followed the actress paparazzi-style when she was living in New York City during the mid-‘50s.

Not only did Monroe graciously welcome them and know their names, but she provided them special access to her and posed for countless candid shots. The documentary reveals many of those rare photos and autographs were sold at Julien’s Auctions.

A pre-famous Marilyn Monroe. (Getty)

“I know for the auctioneers, this was one of the most fascinating discoveries,” said Kent. “When they went into the collections, they had no idea what they were going to find… The photographs we’re familiar with of Marilyn Monroe are beautifully posed shots. These photographs are candid and they’re not posed. They’re of Marilyn as she is naturally.

“You would think that somebody who takes such careful attention to the way she appears, that she wouldn’t welcome these groupies who followed her around everywhere taking these photographs. But she did. She was very welcoming of them and she encouraged them to take photographs. She always made herself available. There was just something about Marilyn that men and women related to and she touched them in some way. And I think those photographs revealed that.”

However, it was the legendary sheer, body-hugging crystal-emblazoned “birthday dress” that proved to be one of the biggest money-makers of the auction.

“She spent her own money having a dress designed for the celebration,” said Kent. “And this dress was really the closest thing that you could come to being naked on film at that time. It was a power play. She outshone Jackie Kennedy. She kind of outshone JFK himself. She dominated the event. She was on stage for what, a minute, singing ‘Happy Birthday Mr. President.’ But she’s the only thing anyone remembers about that night.

“The surprising thing that comes from her personal items is how deliberate and shrewd Marilyn was about planning her career and how she wasn’t afraid to take risks. We don’t mention this in the documentary, but apparently, when she went to New York, she went to Jackie Kennedy’s hairdresser. The same person who did Jackie Kennedy’s hair did Marilyn Monroe’s hair for that night… She deliberately set out to outshine everyone. And she did. It wasn’t an accident.”

Kent said that while it’s likely there are more unseen Monroe memorabilia just waiting to be discovered, there probably won't be another massive auction that chronicle both her career and life.

Marilyn Monroe is all smiles as she poses with fans in front of the Wilshire Beauty Shop at the premiere of director Jean Negulesco's film "How to Marry a Millionaire" in 1953. (Getty)

“The idea that the really ordinary and the really exceptional, that once belonged to Marilyn, together in the same room? I don’t think that’s ever going to happen again,” said Kent.

“Marilyn Monroe for Sale” airs Sunday, December 23 at 9 p.m. on the Smithsonian Channel.