Roman tour guides lead "Angles and Demons" tour…but use the moment to set folks straight

Guides such as Polzer get into debates with novel-clutching tourists when they (the guides) reveal that the markers in St. Peter’s Square — which Brown says were placed by Bernini as lighting the way to the next stop along the path — were "in reality, … placed there two centuries later by a Vatican scientist."

Other guides, such as Tyson Monfredini of Eternal City Tours (Rome’s Catholic guides), are busy pointing out to Brownies that there never was a church in Piazza Barberini, let alone it being moved.

But architectural faux pas aren’t the biggest problem with fanciful fiction, lamented Monfredini.

He warned of the spiritual damage that can come from using a fictional book as a blueprint guide to the heart of Christendom. It would be a shame, he said, for visitors who come to a place so filled with wondrous artifacts, to not uncover the faith behind the works.

When Monfredini describes the reality of Bernini, the committed family man who followed papal directions, some tourists’ faces drop. "It seems that his being a pro-life Catholic, which is more logically consistent with our evidence, is more exciting these days than his representation as a pagan."