The portico is 110 feet long, and 44 feet deep. Sixteen Corinthian columns, 46½ feet high and 5 feet in diameter, support the roof. The Pantheon was converted into a church by Boniface IV. in 609, by permission of the Emperor Phocas, and it was dedicated to the martyrs on November 1st (All Saints' Day), 830. The doors and grating above, of ancient bronze, with the rim round the circular opening in the vault of the interior, are all that is left of the ancient metal work. The interior is 142 feet in diameter, and 143 feet high, and is lighted by an open space of 28 feet in diameter. It is the burial-place of Raphael and of Victor Emanuel II.--_right of high altar_. Pliny says ("Nat. Hist." xxxvi. 4): "The Pantheon of Agrippa has been decorated by Diogenes of Athens, and the caryatides by him, which form the columns of that temple, are looked upon as masterpieces of excellence. The same, too, with the statues that are placed upon the roof, though, in consequence of the height, they have not had an opportunity of being so well appreciated." "The capitals, too, of the pillars which were placed by M. Agrippa in the Pantheon, were made of Syracusan metal" (_ibid._, xxxiv. 7). Marcellinus (xvi. x. 14) says: "The Pantheon, with its vast extent, its imposing height, and the solid magnificence of its arches, and the lofty niches rising one above the other like stairs, is adorned with the images of former emperors." "It is as difficult to reconcile the statements of different authors respecting the original idea of Agrippa, as it is hazardous to attempt to prove the successive metamorphoses which the plan sketched by the artist has undergone. This much, however, is certain, that with respect to the modern transformation of the whole, the consequences have been most melancholy and injurious. The combination of the circular edifice with the rectilinear masses of the vestibule, notwithstanding all the pains bestowed, and the endless expenditure of the most costly materials, has been unsuccessful; and the original design of the Roman architect has lost much of its significance, or, at all events, of its phrenological expression, by being united with ordinary Grecian forms of architecture, which in this place lose great part of their value. No one previously unacquainted with the edifice could form an idea, from the aspect of the portico, of that wondrous structure behind, which must ever be considered as one of the noblest triumphs of the human mind over matter in connection with the law of gravity. "Conflagrations, earthquakes, sacrilegious human hands, and all the injuries of time, have striven together in vain for the destruction of this unique structure. It has come off victorious in every trial; and even now, when it has not only been stripped of its noblest decorations, but, what is still worse, been decked out with idle and unsuitable ornaments, it still stands in all its pristine glory and beauty.