User: What is the mona lisa?
Assistant: The Mona Lisa is one of the rarest and most valuable paintings in history.  It was painted by  Leonardo da Vinci in 1503.  Appraisers also say the Mona Lisa is priceless, but if it was ever auctions that it would be worth more than a billion dollars.  The Mona Lisa is currently on display at the Louvre Museum in Paris, France.  You can pay for a tour of the Louvre Museum and at the end of the tour or walk through you get to see the Mona Lisa.