"The cause of final ruin to this monument" is described by Nibby to have been the resentment of the citizens against a French governor who espoused the cause of the anti-pope (Clement VII.) against Urban VI. in 1378. It was then that the marble casings were all torn from the walls and used as street pavements.
A drawing of Sangallo of 1465 shows the "upper part of the fortress crowned with high square towers and turreted buildings; a cincture of bastions and massive square towers girding the whole; two square-built bulwarks flanking the extremity of the bridge, which was then so connected with these outworks that passengers would have immediately found themselves inside the fortress after crossing the river. Marlianus, 1588, describes its double cincture of fortifications—a large round tower at the inner extremity of the bridge; two towers with high pinnacles, and the cross on their summits, the river flowing all around."[321]
The castle began to assume its present aspect under Boniface IX. in 1395. John XXIII., 1411, commenced the covered way to the Vatican, which was finished by Alexander VI.; and roofed by Urban VIII., in 1630. By the last-named pope the great outworks of the fortress were built under Bernini, and furnished with cannon made from the bronze roof of the Pantheon. Under Paul III. the interior was decorated with frescoes, and a colossal marble angel erected on the summit, in the place of a chapel (S. Angelo inter Nubes), built by Boniface IV. The marble angel was exchanged by Benedict XIV. for the existing angel of bronze, by a Dutch artist, Verschaffelt.
"Paul III. voulant justifier le nom donné à cette forteresse, fit placer au sommet de l'édifice une statue de marbre, représentant un ange tenant à la main une épée nue. Cet ouvrage de Raphaël de Montelupo a été remplacé, du temps de Benoit XIV., par une statue de bronze qui fournit cette belle réponse à un officier français assiégé dans le fort. 'Je me rendrai quand l'ange remettra son épée dans le fourreau.'
" ... Cet ange a l'air naïf d'une jeune fille de dix-huit ans, et ne cherche qu'à bien remettre son épée dans le fourreau."—Stendhal, i. 33.
"I suppose no one ever looked at this statue critically—at least, for myself, I never could; nor can I remember now whether, as a work of art, it is above or below criticism; perhaps both. With its vast wings, poised in air, as seen against the deep blue skies of Rome, or lighted up by the golden sunset, to me it was ever like what it was intended to represent—like a vision."—Jameson's Sacred Art, p. 98.
Of the castle, as we now see it externally, only the quadrangular basement is of the time of Hadrian; the round tower is of that of Urban VIII., its top added by Paul III. The four round towers of the outworks, called after the four Evangelists, are of Nicholas V., 1447.
The interior of the fortress can be visited by an order. Excavations made in 1825 have laid open the sepulchral chamber in the midst of the basement. Here stood, in the centre, the porphyry sarcophagus of Hadrian, which was stolen by Pope Innocent II. to be used as his own tomb in the Lateran, where it was destroyed by the fire of 1360, the cover alone escaping, which was used for the tomb of Otho II., in the atrium of St. Peter's, and which, after filling this office for seven centuries, is now the baptismal font of that basilica. A spiral passage, thirty feet high, and eleven wide, up which a chariot could be driven, gradually ascends through the solid mass of masonry. There is wonderfully little to be seen. A saloon of the time of Paul III. is adorned with frescoes of the life of Alexander the Great, by Pierino del Vaga. This room would be used by the pope in case of his having to take refuge in S. Angelo. An adjoining room, adorned with a stucco frieze of Tritons and Nereids, is that in which Cardinal Caraffa was strangled (1561) under Pius IV., for alleged abuses of authority under his uncle, Paul IV.—his brother, the Marquis Caraffa, being beheaded in the castle the same night. The reputed prison of Beatrice Cenci is shown, but it is very uncertain that she was ever confined here,—also the prison of Cagliostro, and that of Benvenuto Cellini, who escaped, and broke his leg in trying to let himself down by a rope from the ramparts. The statue of the angel by Montelupo is to be seen stowed away in a dark corner. Several horrible trabocchette (oubliettes) are shown.
On the roof, from which there is a beautiful view, are many modern prisons, where prisoners suffer terribly from the summer sun beating upon their flat roofs.
Among the sculptures found here were the Barberini Faun, now at Munich, the Dancing Faun, at Florence, and the Bust of Hadrian at the Vatican. The sepulchral inscriptions of the Antonines existed till 1572, when they were cut up by Gregory XIII. (Buoncompagni), and the marble used to decorate a chapel in St Peter's! The magnificent Easter display of fireworks (from an idea of Michael Angelo, carried out by Bernini), called the girandola, used to be exhibited here, but now takes place at S. Pietro in Montorio, or from the Pincio. From 1849 to 1870, the castle was occupied by French troops, and their banner floated here, except on great festivals, when it was exchanged for that of the pope.