While Dan Brown's books may make for good readin' (or not) they shouldn't be used to ascertain historical facts. I've already made some posts about The Da Vinci Code. This article from the UK's Telegraph newspaper gives a list of 50 of the more grievous ones: The Lost Symbol and The Da Vinci Code author Dan Brown: 50 factual errors

I'm not posting this to poke fun at Dan Brown, or take pleasure in pointing out his mistakes. Nor am I confused about the status of Brown's books as being fiction. So responses of "IT'S ONLY A FICTION BOOK GET OVER IT" are not welcome or helpful. Although well aware that Brown's books are fictional, many people DO believe at least parts of them are accurate. An example is my former co-worker who, upon learning I am a Christian, said something to the effect of "Oh I guess you haven't read The Da Vinci Code, it destroys Christianity!"

Of course after he saw The Real Da Vinci Code program on TV and got the facts he changed his mind. But it illustrates the need for proper information.