If you ever visit Rome, I highly recommend that you get to the Trastevere neighborhood which is located on the other side of the Tibor River. It feels like the Italy you've come to expect from movies and media. It has cobblestone streets, old churches, ivy/vines growing on the medieval buildings, and plenty of good cafe/restaurants (including my favorite Forna la Renella).
At the heart of the Trastevere neighborhood is the Basilica di Santa Maria and is said to be the first place where mass was celebrated and the first church dedicated to Mary. The basic floor plan and structure date back to the 340's
They say the mosaic on the church's facade dates back to the 12th century.
The mosaics inside the church date back to the 13th century.