The Sistine Chapel ceiling and lunettes, painted by Michelangelo between 1508 and 1512.
On Nov. 1, 1512, Pope Julius II held the first Mass in the Chapel for All Saint's Day. The central ceiling panels depict the stories of Genesis, from the separation of light and darkness to the drunkenness of Noah.
The authors of a new book, "The Sistine Secrets: Michelangelo's Forbidden Messages in the Heart of the Vatican," say that Michelangelo embedded powerful and even dangerous messages in the frescoes of the Sistine Chapel, that he encoded these messages using his knowledge of mystical Jewish texts and that he intended some images as insults to the pope himself. (Michelangelo Buonarroti/BridgemanArtLibrary/Getty Images)