The Mona Lisa was one of Leonardo's favourite paintings, and he carried it with him until he died. Today, it is regarded as the most famous painting in the world, and is visited by many thousands of people every year.
Who is this familiar figure? Many suggestions have been made, but the most likely candidate is Lisa Gherardini, the wife of a Florentine silk merchant. Another more unlikely - but popular - theory is that the painting was a self portrait.
There are certainly similarities between the facial features of the Mona Lisa and of the artist's self portrait painted many years later. Could this be why Leonardo gave the subject such an enigmatic smile? Today, the Mona Lisa looks rather sombre, in dull shades of brown and yellow. This is due to a layer of varnish covering the paint, which has yellowed over the years. It is possible that the painting was once brighter and more colourful than it is now.
The Mona Lisa was stolen from the Louvre in 1911, by a former employee who believed the painting belonged in Italy. The thief walked out of the gallery with the picture underneath his painter's smock. He was apprehended by police two years later, and the painting safely returned. (BBC)