The first church on this site was founded probably in the 3rd century, by Pope Urban I; it was devoted to the Roman martyr Cecilia, martyred it is said under Marcus Aurelius Severus Alexander, by the late fifth century, for in the synod of 499 of Pope Symmachus, the church is indicated with the Titulus Ceciliae. Tradition holds that the church was built over the house of the saint. The baptistery associated with this church, together with the remains of a Roman house of the early Empire, was found during some excavations under the Chapel of the Relics. On 22 November 545, Pope Vigilius was celebrating the saint in the church, when the emissary of Empress Theodora, Antemi Scribone, captured him.