The Sixteenth Century was the time period of famous artists such as Leonardo da Vinci, Raphael and Michelangelo. Some of their works from this century include da Vinci's "Mona Lisa," Raphael's "The Small Cowper Madonna" and the Sistine Chapel ceiling, painted by Michealangelo (who, by the way, hated every minute of it).
The Mona Lisa was never given to the one who commissioned it. Instead, da Vinci carried it with him for the remainder of his life. Personally, while the piece is beautiful, it is simultaneously slightly disconcerting and almost creepy with how she stares directly yet indirectly at the viewer. Combine that with the soft smile (which would be okay if the eyes were different) and it gets ever so slightly uncomfortable to study.