The old Basilica of S. Peter on the Vatican is said to have been built during the reign of Constantine, and to have been consecrated in 324 A.D. It was one of the largest of those Roman buildings, measuring 435 feet in length from the great door to the end of the tribune. A spacious open square or atrium, surrounded by a cloister-portico, gave access to the church. This, in the Middle Ages, gained the name of the Paradiso. A kind of tabernacle, in the centre of the square, protected the great bronze fir-cone, which was formerly supposed to have crowned the summit of Hadrian's Mausoleum, the Castle of S. Angelo. Dante, who saw it in the courtyard of S. Peter's, used it as a standard for his giant Nimrod. He says-- _La faccia sua ml parea lunga e grossa, Come la pina di San Pietro a Roma. --(Inf._ xxxi. 58.) This mother-church of Western Christendom was adorned inside and out with mosaics in the style of those which may still be seen at Ravenna. Above the lofty row of columns which flanked the central aisle ran processions of saints and sacred histories. They led the eye onward to what was called the Arch of Triumph, separating this portion of the building from the transept and the tribune. The concave roof of the tribune itself was decorated with a colossal Christ, enthroned between S. Peter and S. Paul, surveying the vast spaces of his house: the lord and master, before whom pilgrims from all parts of Europe came to pay tribute and to perform acts of homage. The columns were of precious marbles, stripped from Pagan palaces and temples; and the roof was tiled with plates of gilded bronze, torn in the age of Heraclius from the shrine of Venus and of Roma on the Sacred Way.