On March 18, 1990, a brazen art heist stripped Boston's Isabella Stewart Gardner Museum of 13 of its master works of art, kicking off a winding investigation that would rope in wannabe rock stars, menacing mobsters, and a cavalcade of colorful characters. It was the biggest art heist in history, and now it's the subject of This Is a Robbery: The World’s Biggest Art Heist, a new Netflix docuseries.

Whether or not you’ve cracked into this tantalizing true crime miniseries, you might well wonder how so many coveted masterpieces could vanish without a trace. To this day, the case remains unsolved, as do many of the smaller mysteries surrounding it. But there’s plenty that is known about what went down in Boston that St. Patrick's Day weekend—and it's absolutely mind-blowing.

1. The Isabella Stewart Gardner Museum is an eccentric spot that was inspired by its creator's world travels.

The Isabella Stewart Gardner Museum in 1904, as viewed from the Back Bay Fens.Detroit Publishing Company, Library of Congress, Public Domain // Wikimedia Commons

On April 14, 1840, Isabella Stewart was born into a wealthy New York City family who made sure that Isabella got the best education money could buy. In 1860, following her marriage to John “Jack” Lowell Gardner Jr.—a prominent Boston businessman, philanthropist, and art collector—the stylish, 20-year-old socialite moved to Massachusetts. The couple spent the next several decades traveling the world, where Isabella reveled in the art and architecture she saw—especially the Palazzo Barbaro, a pair of adjoining palaces in Venice, Italy—all of which inspired what would eventually become her museum.

Following the death of her husband in 1898, Isabella bought a plot of undeveloped land in Boston's Back Bay Fens area, which was surrounded by swamp. There, she built a palace of her own that incorporated both Renaissance and European Gothic design elements. The bottom three floors were filled with Isabella's growing collection of paintings, sculptures, tapestries, furniture, manuscripts, rare books, and decorative arts; the fourth floor served as her private residence.

2. Isabella Stewart Gardner dedicated the last quarter-century of her life to her museum.

Stewart, who passed away in 1924, spent the last 25-plus years of her life dedicating herself to the museum, mindfully rearranging its layout to exhibit new additions to her collection, hosting concerts and lectures, and urging artists and the public to enjoy and be inspired by one of the most extraordinary private art collections in America.

"It’s not a museum,” biographer Patricia Vigderman proclaims in the Netflix docuseries. "It’s her work of art, an architectural spectacle."

3. Isabella Stewart Gardner's will made a very specific stipulation about her museum.

John Singer Sargent was a close friend of Isabella Stewart Gardner, and her museum's first artist in residence. She is the subject of his 1922 painting, Mrs. Gardner in White.John Singer Sargent, Public Domain // Wikimedia Commons

To preserve her work on the museum itself—along with the many priceless pieces of art contained within it—Stewart created an extraordinary declaration in her will: The museum was never to change. "She said if anything were permanently changed, the collection should be crated, shipped to Paris for auction, and the money should go to Harvard University,” Anne Hawley, who served as the museum's director from 1989 to 2015, explained in This Is A Robbery. So, until the robbery in 1990, not a single one of the 2500 works within the Gardner Museum’s walls had ever left the grounds or even been moved.

4. It took just 81 minutes to pull off the world’s biggest art heist.

On March 18, 1990, at 1:24 a.m., two men gained entrance to the Isabella Stewart Gardner Museum. In less than 90 minutes, they made off with 13 works of art, which at the time were collectively valued at $200 million (today, they're worth $500 million).

The inventory of stolen items included paintings, sketches, a 12th century Chinese beaker, and an eagle finial from a flag pole of the first regiment of Grenadiers of Foot of Napoleon’s Imperial Guard. Among the snatched paintings, there was Johannes Vermeer’s The Concert, Govaert Flinck’s Landscape With an Obelisk, and Édouard Manet’s Chez Tortoni. Five pieces by Edgar Degas were stolen (Three Mounted Jockeys, Leaving The Paddock, Procession on a Road Near Florence, and a pair of sketches titled Study for The Programme) along with three works by Rembrandt: the etching Portrait of the Artist as a Young Man, the painting A Lady and Gentleman in Black, and Christ In The Storm On the Sea of Galilee—which was the most valuable artwork of all, as it's the artist’s only known seascape.

Days after the heist, the museum offered a $1 million reward for information leading to the return of these works. By 1997, they had upped the ante to $5 million. In 2017, Smithsonian Magazine reported that the reward was now $10 million. Still, there were no takers.

5. Some people believe the thieves had a “hit list” of pieces.

An FBI poster featuring Rembrandt's Christ in the Storm on the Sea of Galilee, the most valuable of the museum's stolen works.FBI, Public Domain // Wikimedia Commons

One of the first questions raised was why the thieves chose the pieces that they did. As suggested by the leisurely 81 minutes, this was not a smash-and-grab heist, where they grabbed the easiest works to steal or pieces nearest the exit. The stolen items were spread across three galleries on two separate floors. The thieves smashed glass panels, tore down frames, and sloppily sliced paintings from their canvases. This suggests that they knew what they wanted, but not how such damage would affect the worth of their haul. Plus, they overlooked the museum’s most highly valued asset, Titian’s The Rape of Europa, in favor of less expensive pieces. Thus, Hawley speculated that the thieves had a “hit list,” telling The New York Times in 1990 that she suspected they were working under the direction of a private collector.

The audacity of the heist seems to support this theory. After all, the paintings could not have been sold legally, what with the FBI on the hunt and the whole world caught up in news about the world's biggest art heist. However, John Walsh, director of the J. Paul Getty Museum in Los Angeles, scoffed at this “hit list” theory back in 1990. "Every time there's a thief, there's a James Bond theory,” he told The Washington Post, referencing Dr. No. “So far, we've never found the demented billionaire on a submarine off Uruguay, or wherever he is supposed to be."

6. The thieves came into the Isabella Stewart Gardner Museum disguised as cops.

It was St. Patrick’s Day weekend in Boston, but the street where the museum is located was far from the carousing crowds. There, two men dressed as police officers rang the bell at the side door of the museum. After being buzzed in by security, they lured the two on-duty guards away from their stations and handcuffed them both. Then, one of the counterfeit cops announced: "Gentlemen, this is a robbery."

The museum's night watchmen, who were caught off-guard, were escorted to the basement, where the crooks bound them in place with duct tape. For hours after the thieves had made off with their loot, the guards were left under the museum, awaiting rescue. When the morning shift showed up, they found the security office door smashed open, golden frames scattered on the floors, and the two guards—rattled but alive—in the basement.

7. The FBI suspected that one of the Isabella Stewart Gardner Museum's security guards could have been an inside man.

Several clues suggested that the thieves knew too much about how the museum’s security worked. In one gallery, they’d left a secret door ajar. They also knew where the security footage was recorded and made sure to snatch those VHS tapes as well as the printouts that reported on motion detectors going off in the galleries. Plus, it was against protocol to let anyone in through the side door, so why did this duo feel confident that was the best approach?

All of these factors led the FBI to take a closer look at Richard Abath, the guard who had let the men in. Those suspicions were reignited 25 years after the robbery, when the FBI released security footage (above), which showed Abath breaking side-door protocol the night before the robbery. However, since no concrete evidence proves he was involved, Abath has never been charged.

The Netflix doc paints Abath not as an accomplice, but as a hapless wannabe rock star and admitted stoner, who’d previously given notice at the museum so that he could focus on his band. "I was just this hippie guy who wasn't hurting anything, wasn't on anybody's radar,” Abath told NPR in 2015. “And the next day I was on everybody's radar for the largest art heist in history."

8. The Isabella Stewart Gardner Museum was not insured for theft, despite an FBI warning that it was being cased.

Two years before the heist, the museum board was informed that the FBI had thwarted a plot to steal from the Gardner Museum—so it might seem strange they hadn’t invested in theft insurance. Days after the heist, The New York Times detailed two very good reasons why the museum might have opted to forgo insurance, the first one being cost. "The Gardner Museum's annual operating budget is $2.8 million,” museum spokesperson Barry Wanger told the paper, “while the cost of theft insurance could run to $3 million or more a year."

The Washington Post reported that remaining uninsured was a common practice among museums, writing that, “Many museums carry no insurance on their collections, according to experts, because the objects are irreplaceable and many museum directors prefer to spend the tens of thousands they would need for premiums on salaries for extra guards."

The other reason was Gardner’s will. The purpose of theft insurance is to give a museum money so they might replace the lost artwork with something of like value. However, The New York Times reporter Fox Butterfield wrote that “Mrs. Gardner's strictly worded will specifies that the museum may not buy new or substitute works of art and so would not be allowed to replace stolen paintings even if the museum had insurance."

9. The FBI investigated a notorious art thief, as well as the mob.

In 1975, Myles Connor Jr. stole a Rembrandt from Boston's Museum of Fine Arts, which is just a short walk from the Gardner Museum. So when the latter was burgled, Connor became an immediate suspect ... except he had a superb alibi: He was already in federal custody. "There’s a saying that the guards came to knock on my cell door, to make sure I was there," Connor says in This Is a Robbery.

Still, authorities believe Connor was an inspiration to the Gardner Museum thieves. When he was collared for another crime, he used the location of the stolen Rembrandt as a bargaining chip to half his prison sentence. “I got the idea from an FBI agent,” Connor told the Netflix crew. “He said, ‘It’s gonna take a Rembrandt to get you out of this one.’ And I said, 'OK.'"

Connor further speculated that the 13 Gardner pieces might have been used as collateral in the mob’s cocaine deals. If a buyer didn’t have enough cash to lay down for a big haul, the seller could “hold the art (worth millions) until they’re reimbursed for whatever the value of the cocaine is.” This might have been the motive, but it didn’t narrow down the list of suspects. Among those now known to have been investigated were mobsters like Robert Guarente, Robert Gentile, and James “Whitey” Bulger, and then there was William P. Youngworth, a petty criminal who claimed he could recover 11 of the pieces in 2013. Yet no charges were filed.

10. The FBI claimed they know who pulled off the Isabella Stewart Gardner Museum heist, but wouldn’t say who … at first.

On March 18, 2013, 23 years into the investigation, the FBI announced they had traced the stolen items from Boston to Connecticut to Philadelphia, where the trail went cold. "We have identified the thieves, who are members of a criminal organization with a base in the mid-Atlantic states and New England,” Richard DesLauriers, a special agent in charge of the FBI’s Boston office, proclaimed. At the time, he declined to name the thieves, then appealed to the public for information they might have about one of the FBI’s Top Ten Art Crimes.

In 2015, the FBI provided an update: The thieves had been identified, but were dead. Artnet News reported that George Reissfelder and Lenny DiMuzio, cohorts of known crime lord Carmello Merlino, were the culprits. Longtime suspects, both died within a year of the heist (the former from a drug overdose; the latter was murdered). Merlino could not be questioned either: He died of natural causes in 2005. The whereabouts of the stolen art remains unknown.

11. The frames surrounding the stolen pieces have sat empty ever since the robbery.

An empty frame remains where Rembrandt's The Storm on the Sea of Galilee was once displayed at the Isabella Stewart Gardner Museum.FBI, Public Domain // Wikimedia Commons

Six days after the heist, the museum reopened to the public. Management addressed the losses as best they could while respecting Gardner's will. Thus, the frames were rehung—just without the stolen art inside them. Robbed of their canvases, the frames display the ornate wallpaper that lies behind them. And so it has been for more than 30 years, leaving a striking reminder of what was lost.

Thanks to modern innovations, you don't need to travel to Boston to go on a tour that focuses on the stolen art. Google Arts and Culture presents an interactive option, where art lovers can click and drag to look around the galleries, while side panels provide information on the building’s history, the heist, the missing works, and more.

12. The statute of limitations has expired on all crimes related to the Isabella Stewart Gardner Museum heist, but the search for the stolen art continues.

According to The New York Times, the statute of limitations has expired on all crimes that could be tied to the Gardner Museum Heist. This means that even someone who was involved could come forward to claim the reward, which still stands at $10 million in exchange for information that leads to the safe return of the stolen works of art. A separate reward of $100,000 is available for the return of the Napoleonic eagle finial. On the Gardner Museum website, anyone with information about the stolen artworks is encouraged to contact the director of security via e-mail: reward@gardnermuseum.org.

As their focus is on the recovery of these pieces for public display, the museum’s staff promises, “Confidentiality is assured.”