This book is obviously a labor of love. The authors know the area well, and in detail. They appreciate all the layers of culture, from prehistoric through Etruscan and ancient Roman right down to modern life. I spent a week bicycling in Lazio using this guide, and was never disappointed. In addition, you will want to have a good map (e.g. the TCI 1:200,000 map) and perhaps a restaurant guide if eating well is important to you.

This is a plain print book, with few illustrations or diagrams, but with a useful table to help you find places that interest you (e.g. Renaissance gardens).

A pity it's out of print.