More than $850 million — that's the estimated value of the legendary Mona Lisa painting. Nevertheless, one of the most famous paintings and an iconic Renaissance art piece is not for sale. Under French heritage law, an artwork declared priceless is prohibited from being bought or sold. Although you might not be able to take the painting home, you can still take a glimpse at the iconic smiling lady in the Louvre for less than the cost of a meal at Mickey D's.