Sometimes, the real thing is so fascinating that a fictional version can't come close. There's a book by Luc Sante called "Low Life". It's a history of New York's seemier side from the New Amsterdam days up through the 1920's. It beats out any fiction about New York.

I have the same feelings about the Mafia - Good Fellas was a great movie, and the book it's based on - Wise Guys - was even better. The Godfather left me cold. The difference between real and fictional Mafia is like the difference between really good European chocolate and a bottle of YooHoo.