It is believed that Leonardo da Vinci began working on the Mona Lisa around 1503 and continued working on it intermittently for several years. There is no definitive date that marks the completion of the painting.
- Some sources, like the Louvre Museum, state that it was "doubtless painted between 1503 and 1506".
- Other art historians believe that he might have continued working on it as late as 1517.