Hidden Gems in Rome's alleyways

One of the things I enjoyed most in Rome was getting up early and wandering all the little alleys in the cool of the morning before all the crazy traffic started and when there was hardly anyone around, only the early workers heading off to work.
All the alleyways had hidden gems - some had beautiful Churches tucked away with magnificent interiors, some just old apartments with fabulous old doors or tiny little grottos up really high in the walls. These little grottos always had small marble carvings in them - it would be so interesting to know the history behind them. Cars were always parked on footpaths and it was always so cool and peaceful compared to the heat of the days. This place had these lovely old carved sections(most probably marble) around the door. Marble is everywhere in Italy, even on the pavements and road edges. It's such a different way of life to ours and it was wonderful to be there and see it all.
Edit: I went back and enlarged the photo and read the little sign on the door and it said "Sala Margana" so I googled it and found some interesting information.
Sala Margana info here