The Mona Lisa by Leonardo da Vinci is a well known, highly recognizable piece of Renaissance art that is housed in the Louvre Museum in Paris, France. To complicate the issue, the art world is known for its complexities, there are works of art which are considered in the public domain. For instance, the image of the Mona Lisa is in the public domain.
Most people know what the image looks like and it can be used without issue.
The painting by Leonardo da Vinci is owned by the Louvre Museum in Paris but its image is in the public domain. This is basically why you will find Mona Lisa's image on everything from t-shirts to jars of tomato sauce. The same thing applies to the famous painting of a farming couple with a pitchfork called American Gothic . Like Lisa, those folks have been the selected image for many advertisements. The painting is by the American Regionalist painter from Iowa, Grant Wood, who was active in the 1930s and worked within the stylistic circle of John Steuart Curry and Thomas Hart Benton.