The present church was formed out of the great hall of the Baths of Novatus after A.D. 108; the baths being erected in the time of Domitian adjoining the house of Pudens, who founded in his house a Christian oratory before A.D. 96. This oratory exists below the present church, which was formed by Bishop Pius, who died in A.D. 157. The church below is the oldest Christian church in the world, and existed in the time of S. Paul, who, writing to the Romans (xvi. 13), says, "Salute Rufus chosen in the Lord, and his mother and mine." This Rufus was Aulus Rufus Pudens, who held an official position in the southern province of Britain, and married Gladys (Claudia), the daughter of Caractacus, the British chief. He was likewise half-brother of S. Paul, and the friend of Martial the poet. The apostle, writing to Timothy from Rome (2 Tim. iv. 21), says, "Eubulus greeteth thee, and Pudens, and Linus, and Claudia, and all the brethren." Linus was the second son of Caractacus, and was the first bishop of the Church of Rome ordained by Paul. From Cyllinus, the eldest son of Caractacus, descended Constantine the Great, born and bred, and proclaimed emperor, in Britain. Thus the first Bishop of Rome and the first Christian emperor were undoubtedly Britons of royal British blood. In the tribune of the church is a beautiful mosaic of the time of Adrian I., A.D. 772-795, who built the apse inside the wall of the large hall. The old wall can be seen on the outside, the mosaic representing our Saviour on a throne, with four of the apostles on each side, and Pudentia and Praxedes behind; the paintings above are by Pomarancio. In the left aisle is a well, containing, it is said, remains of the martyrs--some remains are shown. At the end of this aisle is the chapel of S. Peter; the mosaic pavement belonged to the baths. On the left is a copy of the inscription from the catacomb of S. Priscilla: "BENE MERENTI CORNELIÆ PUDENZIANÆ." Under the altar is a sponge said to have been used by the two sisters to collect the blood of the martyrs. Above is a relief, by Giacomo della Porta, of Peter receiving the keys from Christ. On the left of this aisle opens the Chapel of the Gaetani--rich in marbles. The roof is in mosaic, representing the four Evangelists, and over the door are representations of the sisters Pudentia and Praxedes collecting the blood of martyrs. They are by Rossetto, designed by F. Zuccari (1600). The altar-piece, by Paolo Olivieri, is the Adoration of the Magi. _For a more detailed account of this interesting church, see our_ "Footsteps of S. Paul in Rome." Retracing our way down the Via Urbana, we come to where the Via di S. Lucia in Selci goes off at an angle to the left. Here was THE SCENE OF TULLIA'S IMPIETY.