Story highlights The Mona Lisa is the most famous painting in the world. But why?

Theft over 100 years ago helped catapult artwork to international stardom

Leonardo da Vinci's masterpiece now attracts millions of visitors to Louvre

Why is the Mona Lisa the most famous painting in the world?

Her enigmatic smile? The mystery surrounding her identity? The fact she was painted by Renaissance pin-up boy Leonardo da Vinci?

Sure, all of these things helped boost the popularity of the 16th century masterpiece.

But what really catapulted the small, unassuming portrait to international stardom was a daring burglary over 100 years ago.

When Italian handyman Vincenzo Peruggia stole the Mona Lisa from the Louvre in 1911, he never could have guessed her absence would be the very thing that made her the most recognizable painting on the planet.

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Photos: Notorious art heists Photos: Notorious art heists In 1911, Leonardo Da Vinci's "Mona Lisa" was stolen from the Louvre by an Italian who had been a handyman for the museum. The now-iconic painting was recovered two years later. Hide Caption 1 of 12 Photos: Notorious art heists A statue called "Young Girl With Serpent" by Auguste Rodin was stolen from a home in Beverly Hills, California, in 1991. It was returned after someone offered it on consignment to Christie's auction house. Rodin, a French sculptor considered by some aficionados to have been the father of modern sculpture, lived from 1840 until 1917. His most famous work, "The Thinker," shows a seated man with his chin on his hand. Hide Caption 2 of 12 Photos: Notorious art heists Picasso's "La Coiffeuse" ("The Hairdresser") was discovered missing in 2001 and was recovered when it was shipped from Belgium to the United States in December 2014. The shipper had listed the item as a $37 piece of art being sent to the United States as a Christmas present. Hide Caption 3 of 12 Photos: Notorious art heists Italy's Culture Ministry unveils two paintings by the French artists Paul Gauguin and Pierre Bonnard on April 2, 2014. The paintings were stolen from a family house in London in 1970, abandoned on a train and then later sold at a lost-property auction, where a factory worker paid 45,000 Italian lira for them -- roughly equivalent to 22 euros ($30) at the time. Hide Caption 4 of 12 Photos: Notorious art heists A 19th-century Renoir painting was stolen from a US museum in 1951 and then bought at a flea market in 2010. A judge later ruled that it to be returned to the museum. The 5½-by-9-inch painting, titled "Landscape on the Banks of the Seine," was bought for $7 at a flea market by a Virginia woman. Hide Caption 5 of 12 Photos: Notorious art heists Seven famous paintings were stolen from the Kunsthal Museum in Rotterdam , Netherlands, in 2012, including two Claude Monet works, "Charing Cross Bridge, London" and "Waterloo Bridge." The other paintings, in oil and watercolor, were Picasso's "Harlequin Head," Henri Matisse's "Reading Girl in White and Yellow," Lucian Freud's "Woman with Eyes Closed," Paul Gauguin's "Femme devant une fenêtre ouverte, dite la Fiancee" and Meyer de Haan's "Autoportrait." Hide Caption 6 of 12 Photos: Notorious art heists A Salvador Dali painting stolen from a Manhattan art gallery by a man posing as a potential customer in 2012 . It was later intercepted by customs police after it was sent back to the United States from Greece. Hide Caption 7 of 12 Photos: Notorious art heists In 1473, Hans Memling's "The Last Judgment" was stolen by pirates and became the first documented art theft. Hide Caption 8 of 12 Photos: Notorious art heists Adam Worth, the inspiration for Sir Arthur Conan Doyle's diabolical character Moriarty, stole "Georgiana, Duchess of Devonshire," painted by Thomas Gainsborough in 1876. Hide Caption 9 of 12 Photos: Notorious art heists The Nazis plundered countless precious artworks during World War II, including "Adele Bloch-Bauer I," by Austrian artist Gustav Klimt, which was confiscated from the owner as he fled Austria. Hide Caption 10 of 12 Photos: Notorious art heists Many works of art that were taken by the Nazis were never recovered. Others were returned after years of legal battles. "Christ Carrying the Cross," by Italian artist Girolamo de' Romani, was returned to its owner's family in 2012. Hide Caption 11 of 12 Photos: Notorious art heists A version of Edvard Munch's "The Scream" was one of two paintings by the artist to be stolen from the Munch Museum in Oslo, Norway, in 2004. Hide Caption 12 of 12

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Suddenly images of the artwork were splashed across international newspapers, as the two-year police hunt hit dead-end after dead-end.

It wasn't until December 1913 -- exactly 100 years ago next month -- that Peruggia was finally caught and the Mona Lisa recovered, becoming the best known painting in a time before we shared images on TV, internet, and phones.

Today, she is the jewel in the Louvre's crown, helping attract over 9.7 million visitors to the Paris museum last year, and immortalized in everything from Andy Warhol's pop art to Dan Brown's bestselling novel, "The Da Vinci Code."

But had Peruggia instead slipped another artwork under his cloak that fateful day, it could have been a very different story.

"If a different one of Leonardo's works had been stolen, then that would have been the most famous work in the world -- not the Mona Lisa," said Noah Charney , professor of art history and author of "The Thefts of the Mona Lisa."

"There was nothing that really distinguished it per se, other than it was a very good work by a very famous artist -- that's until it was stolen," he added. "The theft is what really skyrocketed its appeal and made it a household name."

Bold burglar

So how did Peruggia pull off one of the greatest art heists of all time? With mind-boggling ease, it seems.

The handyman had been hired by the Louvre to make protective glass cases for some its famous works -- including the Mona Lisa.

After hiding in a closet overnight, he simply removed the painting, hid it under his smock, and was about to waltz out of the building when he discovered the door was locked.

Desperate Peruggia removed the doorknob, but still it wouldn't open -- until a helpful plumber passing by opened the door with his key.

It was 24 hours before anyone even noticed the Mona Lisa was missing, with artworks often removed to be photographed or cleaned.

"The Louvre had over 400 rooms but only 200 guards and even fewer on duty overnight," said Charney, founder of the Association for Research into Crimes against Art (ARCA) . "There were basically no alarms in play."

"It was under-secure. But to be fair, most museums were at that time."

Front page news

The French press had a field day, seeing it as an opportunity to poke fun at the seemingly inept government which ran the Louvre.

This was an era where newspapers were really taking off, and pretty soon the theft -- and the image of the Mona Lisa -- was splashed across the world. "60 detectives seek stolen Mona Lisa, French public indignant," reported the New York Times.

For the first time there were queues outside the Louvre, just to see the empty space where the painting had hung.

"The theft launched it into becoming a household name for people who had never been to Europe and had no interest in art," said Charney, adding: "And it's really just continued from there."

Over the next two years, the bungling police investigation dragged on, with Pablo Picasso a suspect at one point. The force even interviewed Peruggia twice, before concluding he couldn't possibly be the man behind the brazen burglary.

Discovery

The head of the Paris police retired in shame. And then two years later, an art dealer in Florence received a letter from a man saying he had the Mona Lisa. It was signed "Leonardo." The man was of course Peruggia.

After setting up a meeting with the dealer and the director of the Uffizi gallery in Florence, Peruggia turned up with the painting which had spent years hidden in a trunk in his apartment.

Peruggia, then 32 years old, claimed to have stolen the artwork to return her to her native Italy. He was arrested and eventually sentenced to seven months jail.

"He seemed to have genuinely been convinced he would be heralded as a national hero and genuinely dismayed to discover he wasn't," said Charney, adding: "He was maybe a few pickles short of a sandwich, but not a lunatic."

For most of us, the Mona Lisa will only ever be seen from behind bullet-proof glass, a thumbnail in the distance, smiling her knowing-smile behind jostling tourists with camera phones held aloft.

But for over two years Peruggia had the famous woman all to himself. Did he fall in love with her?

"I think so," said Charney. "There are a number of thieves who have stolen art and have suffered a sort of 'reverse Stockholm syndrome' -- where the hostage-taker falls in love with the hostage."

"In this case, the hostage was a work of art."