This book sets the gold standard when it comes to guides to Rome,
This review is from: Blue Guide Rome (Blue Guides) (Paperback)
Comprehensive, detailed, well-written, easy to use, well-researched, regularly updated, thoroughly reliable....the Blue Guide to Rome ticks all of the boxes and towers above its competitors. And the addition, in recent editions, of colour photographs has been the icing on the cake.
I would almost go as far saying that if it is not in the Blue Guide it is not worth seeing. And I speak as a professional, one whose business it is to guide people around the Eternal City.