Mona Lisa
The painting is thought to be a portrait of Lisa Gherardini, the wife of Francesco del Giocondo, and is in oil on a white Lombardy poplar panel. It had been believed to have been painted between 1503 and 1506; however, Leonardo may have continued working on it as late as 1517. Recent academic work suggests that it would not have been started before 1513. It was acquired by King Francis I of France and is now the property of the French Republic, on permanent display at the Louvre Museum in Paris since 1797.
Hugh Blaker
Shortly before World War I, Hugh Blaker discovered a painting of the "Mona Lisa" in the home of a Somerset nobleman in whose family it had been for nearly 100 years. This discovery led to the conjecture that Leonardo painted two portraits of Lisa del Giocondo: the famous one in The Louvre, and the one discovered by Blaker, who bought the painting and took it to his studio in Isleworth, London, from which it takes its name. According to "Encyclopedia Americana" and "The New York Times", The Isleworth Mona Lisa has been attributed to Leonardo, and is thought to be the unfinished portrait from which Raphael made his famous sketch (which is in the Louvre museum), and is in no sense a copy of the Louvre "Mona Lisa".