Considered the most famous painting in the world, the Mona Lisa is one of Leonardo da Vinci's greatest works. He began in 1503 in Florence on a commission for Francesco del Giocondo, and continued to work on over time gradually until his death in 1519. It's full name is Portrait of Lisa Gherardini, wife of Francesco del Giocondo, and it is an oil on poplar wood panel painting. It currently resides in the Louvre museum in Paris, France. It's current valuation is unknown, though its insurance value in 1962 was $100 million ($830 million in 2018 dollars), making it the most valueble painting in the world.
Britannica, The Editors of Encyclopaedia. “Mona Lisa.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 4 Apr. 2019, www.britannica.com/topic/Mona-Lisa-painting.
Image source is Wikimedia Commons, this image is in the public domain.