"A fir tree of prodigious size was used in the vessel which, by the command of Caligula, brought the obelisk from Egypt, which stands in the Vatican Circus, and four blocks of the same sort of stone to support it. Nothing certainly ever appeared on the sea more astonishing than this vessel; 120,000 bushels of lentils served for its ballast; the length of it nearly equalled all the left side of the port of Ostia--for it was sent there by the Emperor Claudius. The thickness of the tree was as much as four men could embrace with their arms." Suetonius ("Claudius," xx.) says: "He sank the vessel in which the great obelisk had been brought from Egypt, to secure the foundation of the mole at Ostia." Pliny (xvi. 76), says: "As to the one in which, by order of the Emperor Caius, the other obelisk had been transported to Rome, it was brought to Ostia, by order of the late Emperor Claudius, and sunk for the construction of his harbour." Marcellinus says: "Subsequent ages to Augustus brought also other obelisks, one of which is in the Vatican." VESTIBULE. Over the entrance _outside_ is a relief of Christ giving the keys to Peter; _inside_ the vestibule is Giotto's (1298) celebrated mosaic, representing our Lord sustaining Peter when he was about to sink whilst walking on the sea. Opposite are the great bronze doors, opened only on special occasions, the work of Antonio Filareto and Simone Donatello in the fifteenth century. The upper panels represent in relief our Saviour and the Virgin, below whom are SS. Peter and Paul; Peter is giving the keys to Pope Eugenius IV. Beneath are the martyrdoms of Peter and Paul: in the former is represented the pyramidal tomb which stood in the Borgo Nuovo, and which was destroyed by Alexander VI. The smaller reliefs represent scenes from the life of the Emperor Sigismund--his coronation, the council of Florence, and his entry into Rome. The framework represents satyrs, nymphs, fauns, Leda and the Swan, Ganymede, the Fox and the Stork, with reliefs of fruit and flowers, and medallions of Roman emperors. The walled-up side door, on the right, is the Porta Santa, which was formerly opened on Christmas-eve of the years of jubilee--every twenty-fifth year. _The first_ inscription relates the gift of olive-yards to provide oil for the lamps given by Gregory II. _The second_, the Bull of Boniface VIII., of the indulgence granted at jubilee. _The third_, Panegyric of Charlemagne on Pope Adrian I. INTERIOR. Five portals give access to the edifice, which faces east. "Enter, its grandeur overwhelms thee not."--BYRON.