And the answer: Mona Lisa.
Long before any cake smearing, the Mona Lisa was stolen in 1911 by Vincenzo Peruggia, an Italian national and a glass cutter for the Louvre where the painting was housed. He felt the Mona Lisa should be brought back to Italy. In 1516, da Vinci originally gave the painting to his French patron King Francois I. Today, the Mona Lisa is at the Louvre since the painting’s return in 1914.
Although the Mona Lisa has since been immortalized for her enigmatic smile — created at the hands of one of the world's most renowned painters, no less — Mona's rise to stardom can, in large part, be attributed to the 1911 theft. The day after Peruggia's crime, French newspapers ran headlines airing critiques of the government for allowing the painting to be stolen. More significantly, though, alongside such headlines was the photo of Mona herself. As the news of the disappearance spread, so too did her image. For the first time, lines formed outside of the Louvre— all in the hopes of seeing the empty space where Mona Lisa once hung.
For many, Mona Lisa then became a household name; a subject of interest. The next two years proved to maintain that status, as French police continued to investigate the case of the stolen da Vinci. At one point in the investigation, Peruggia himself was even questioned before being released.
After several years of searching in vain, the head of the Paris police department retired. Yet, two years later, an art dealer in Florence received a letter from a man saying he had the Mona Lisa. It was signed “Leonardo.” Naturally, it was Peruggia. Mona Lisa was promptly reinstalled in the Louvre, where she remains today.
Learn more about the theft and history of the painting here.