Basilica di San Crisogono

One of Rome's oldest churches, originally founded in the 4th century. The current basilica was rebuilt in 1129 and reworked in the 17th century, but you can descend from the sacristy to the original 4th-century church preserved underneath, with fragments of frescoes, an early font, and a still-standing 9th-century altar. The current upper church is supported by 22 reused ancient columns, has a Cosmatesque floor, and a beautiful gilded 17th-century coffered ceiling. Trastevere; very rarely crowded.