Leonardo started this portrait of Lisa Gherardini, a Florentine merchant’s wife, around 1503, then carried it with him for years and never handed it over. It ended up in France, where he spent his final years.

It became the world’s most famous painting partly by accident: it was stolen from the Louvre in 1911 and missing for two years, front-page news the whole time. Look at the corners of her mouth and eyes, blurred with soft shading (sfumato), which is why her smile seems to change.