After you’ve already visited dozens of Italian churches and think that you may never again need set foot in another chiesa, it’s time to seek out the Basilica of Our Lady in Trastevere and prepare to be wowed. This is one of the oldest churches in Rome and instead of the usual assemblage of Renaissance paintings, the crowning achievement here is the glittering set of Byzantine mosaics. Created by Pietro Cavallini in the 13th century, these masterworks are utterly dazzling.