Italy is more than museums and monuments. Exploring off the typical tourist paths can lead to many surprises and opportunities to meet and interact with the people who live in the city or town you are visiting. Rome is no exception. Away from the traffic and city noise you can find a local street market, a park where locals chat while watching children play or just blend into the daily life of the neighborhood.
Walking away from the Basilica di Santa Maria Maggiore on Via Merulana, take the short parallel street Via di Santa. You will come across the Basilica di Santa Prassede. Look closely as the side entrance is easy to miss.   
Since many Italian churches welcome visitors during the hours they are open, I followed a few locals and visitors inside expecting the usual rows of seats and dark alcoves along the sides. I was greeted by the gleam of thousands of mosaic pieces. I craned my neck to try to see everything. There was no tour guide at the entrance, but I purchased, on the honor system, a brochure within the church.  
The Interior reminded me of the mosaic work in Santa Maria Trastevere in Rome. It was impossible to estimate the number of tiles used in even one picture, let alone the entire ceiling. The stunning pictorials and patterns instead of frescoes or oil paintings is a startling change from other churches in the city.
Santa Prassede offers a unique experience off the beaten paths of Rome. On your next visit, take some time to enjoy the glittering mosaics in each of its chapels, the details on the ceiling and how the clarity of the figures change as you walk closer. It will be a truly unforgettable sight.