Late on the afternoon of Sunday, August 20 1911, three men strolled through the Louvre. Disguising themselves as museum staff they hid until nightfall. Sixteen hours later the most famous painting in the world, the Mona Lisa, had vanished. It took twenty-four hours for anyone in the museum to notice. When the alarm went out, the police rushed to the museum. The doors were locked, staff and visitors were detained, but the painting was long gone. France sealed her borders. And when the museum reopened a week after the theft, Parisians queued up in record numbers to view the blank space where the famous painting once hung. A huge police hunt continued, but months passed with no breakthrough in the case. It seemed that the theft of the Mona Lisa was the perfect crime. Two years later in Florence, art dealer Alfredo Geri received a letter signed 'Leonardo'.The Mona Lisa was for sale; the price half a million dollars. A meeting was arranged and 'Leonardo' was persuaded to let Geri remove the painting and take it to the Uffizi for authentication. The moment Geri left the hotel he called the police. Minutes later 'Leonardo' - aka Vincenzo Peruggia - was arrested. In a further twist, Peruggia was hailed as a national hero in Italy. He portrayed himself as a nationalist, who only stole back what rightly belonged to Italy.The Mona Lisa was brought back to Paris with much fanfare. But what of the other two men from the Louvre heist? Their story is even more incredible. Eduardo de Valfierno, an Argentine con man, was the brains behind the operation. Together with art forger Yves Chaudron, he planned a truly audacious crime. Chaudron forged six copies of the Mona Lisa. They then employed Peruggia to help steal the original. When news of the heist hit the international headlines Eduardo sold the six fakes to wealthy collectors, each of whom believed he was buying the original, netting the equivalent of $90 million in today's money. Neither man was convicted for their part in the theft. The whereabouts of the fakes remains a mystery.