11/10/2026
The Mona Lisa is not painted on canvas. It is painted on wood.
Leonardo da Vinci painted it in oil on a thin panel of poplar, in the early 1500s. It is also smaller than most visitors expect: 77 by 53 centimeters (about 30 by 21 inches).
Wood reacts to its environment in a way canvas does not. Over five centuries, the panel has curved slightly, and there is a crack visible on the back. To keep it from spreading, the reverse side is held by two butterfly-shaped braces and a crossbar.
That is why the painting lives in a sealed, climate-controlled case. Sensors hidden behind the panel constantly monitor temperature and humidity so that neither changes. Once a year, the case is opened so the equipment can be checked, then sealed again.
It is also why the Mona Lisa almost never leaves the Louvre. When an Italian group asked to borrow it in 2011, the museum called it "extremely fragile" and said moving it was out of the question.
The most famous painting in the world is a plank of poplar.