Described as “the best known, the most visited, the most written about, the most sung about, the most parodied work of art in the world”, we are all familiar with the Mona Lisa. However, it's less well-known that two more Mona Lisas have surfaced in recent years, and the people who own them claim they are authentic. Read on as we look at the tangled story behind three versions of the world's most famous painting.