In the first half of the fifteenth century St. Angelo constantly changed hands--now it was retained, now lost, by succeeding popes. The turbulence of the people was uncontrollable and fresh fighting broke out every few weeks. The clash of arms was outdone by the fury of the elements: the tremors of earthquakes shook the city; fierce tempests ravaged it; and great rains fell, followed by disastrous inundations; the peoples’ hearts failed them for fear; eclipses, comets, and other sky portents were frequently to be seen, and close in the wake of these terrors came the dreadful scourges of famine and pestilence. The first ray of hope dawned upon the once splendid city, now little more than an insignificant village, when Pope Nicholaus V was elected in 1447. The annals of the time bear witness to his energy in restoring and embellishing the ruined city of Rome. He cleared out many of the shattered houses, erected churches and palaces, founded the Vatican library, and more particularly devoted himself to the strengthening of St. Angelo. The round towers added to the three angles of the ancient square foundation were his work. He began the brickwork curtain of the circular part of the castle; he gave flanking defence to the entrance of the castle from the bridge of St. Angelo, and he made good the damage done to that bridge by the pressure of the crowd on the occasion of the jubilee commemoration in 1450. Other popes carried on the work; among them Calixtus III, the first of the Borgias, who came to the papal chair in 1455, and Sixtus IV, who employed the celebrated architect and military engineer Antonio da Sangallo to convert the castle into an important and almost impregnable stronghold. Plans and drawings are still extant showing it as it was then, encircled by bastions and massive towers with a line of works joining the defences of the bridge. A fine picture by Carpaccio in the Academy of Fine Arts in Venice has preserved, no doubt faithfully, the aspect of the castle at this time. “Above the circle of the ancient tomb rises a high machicolated square tower occupying almost its entire diameter, and again above this is a second and smaller tower, also machicolated, on the top of which is the figure of the winged angel, the whole surrounded by massive walls, with round towers at each corner. Along the bastions soldiers are blowing trumpets, and flags are flying from the towers. Behind the castle is seen a tall spiral column, on the summit of which stands a naked figure, with a spear and shield, and near it is an octagonal church, surmounted by a narrow dome, both of which, if they ever had an existence out of the mind of the artist, have since utterly disappeared. Ships are also seen lying beyond in the Tiber, from which, apparently, the train of St. Orsola and her bridegroom have just landed. It is marching from them in procession to the broad terrace in front, where the noble couple are