A narrative history of how Leonardo da Vinci's painting of the Mona Lisa came to be the most famous in the world - and one of the most powerful cultural icons of our time. What has made the Mona Lisa the most famous picture in the world? Why is it that, of all the 6000 paintings in the Louvre, it is the only one to be exhibited in a special box, set in concrete and protected by two sheets of bulletproof glass? Why do thousands of visitors throng to see it every day, ignoring the masterpieces which surround it?