A rarity, Santa Sabina is Rome's best remaining example of a paleochristian church. It dates from A.D. 422, and its original wooden doors from that time are still intact. The doors alone are worth the trek here. They are handsomely carved with Bible scenes, including one that depicts the Crucifixion, one of the earliest examples of this in the art of the Western world. You'll find it carved on a door at the end of a "porch" from the 1400s. The porch itself contains ancient sarcophagi.
Santa Sabina was the site of the temple of Juno Regina, the patroness of Rome's Etruscan archrival, Veii, who was seduced into switching sides in 392 B.C. Sabina was martyred to the Christian cause. In 1936 much of the church was restored to its original appearance, and today it is one of Rome's most beautiful churches. The surviving two dozen Corinthian columns might have come from the Temple of Juno. The delicate windows were pieced together from 9th-century fragments. In the floor of the nave is Rome's only surviving mosaic tomb, dating to around 1300.