How It All Goes Down
- Dan Brown lays down some facts, in a prologue to the prologue that is unimaginatively titled "Fact."
- The Priory of Sion is a real secret society, with members that included Sir Isaac Newton, Botticelli, and Leonardo da Vinci (among others).
- The Vatican prelature known as Opus Dei is also a real Catholic sect that's been under scrutiny for the reports of brainwashing, coercion, and corporal mortification.
- All descriptions of artwork, architecture, documents, and secret rituals in the novel are also accurate.