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.
Mona Lisa replicas and reinterpretations
"Mona Lisa" is in the public domain and free to be exploited, explaining its reproduction on everything from postcards to coffee mugs, with no legal repercussions.
Artistic replicas and reinterpretations as a whole – demonstrating adequate modification – are considered "new" works eligible for copyright protection.
A fine example is artist Marcel Duchamp's "L.H.O.O.Q.", a 1919 work of art in which Duchamp embellished existing print-reproductions of Leonardo's "Mona Lisa" by merely adding a goatee ("shown below").
While copyright laws do not protect Leonardo's "Mona Lisa", Duchamp's "L.H.O.O.Q." falls within parameters of copyright law constituting "new" works.
For such reasons, "Mona Lisa" is commonly referenced academically in copyright courses.