The upper chamber, the Memoria, was strengthened with masses of masonry on each side, so as to bear the weight of a great altar, the high altar of the Basilica of Constantine, which was erected so as to stand immediately over the body of S. Peter. A cataract or billicum, as it is sometimes called, covered with a bronze grating, opened from above close to the altar. There are two of these little openings, one leading into the Memoria, and the other from the Memoria to the chamber of the tomb beneath. Through these openings handkerchiefs and such-like objects would be lowered so as to touch the sarcophagus. This we know was not unfrequently permitted in the fifth, sixth, seventh, and eighth centuries. Such objects after they had touched the coffin were esteemed as most precious relics. In addition to these works in the two chambers, the Emperor Constantine enclosed the original stone coffin which contained the remains of S. Peter in bronze, and laid upon this bronze sarcophagus the great cross of gold--the gift of his mother Helena and himself. This is the cross which Pope Clement VIII and his cardinals saw dimly gleaming below, when an opening to the tomb was suddenly disclosed in the great building operations which were carried out during the last years of the sixteenth century. There is scarcely room now for doubt that the bronze coffin and the golden cross are still in the chamber of the tomb where Constantine placed them. When it was found necessary to excavate for the foundation of the new massive baldachino, Pope Urban VIII was alarmed at first lest the sacred tomb should be disturbed. The warnings of Pope Gregory the Great against meddling with the tombs of saints like Peter and Paul being remembered, “no one dare even pray there,” he once wrote, “without much fear.” Three years were spent in preparation for the work and in casting the baldachino. Then the sudden death of Alemanni, the custodian of the Vatican library, who had the chief charge in the preparative work, and the passing away of two of the Pope’s confidential staff just as the work commenced, appalled men’s minds; but after some hesitation it was decided to go on with the necessary excavations--“All possible precautions,” Ubaldi tells us, “being taken for the preservation of the reverence due to the spot, and for the security of the relics.” The Pope commanded, “that while the labourers were at work there should always be present some of the priests and ministers of the Church.” Ubaldi describes at length what was found, when each of the four foundations for the four great columns of the baldachino was dug out. We will quote a few of Ubaldi’s memoranda, and then give a little summary of what apparently was discovered in this perhaps the most ancient, certainly the most interesting, of the subterranean cemeteries of Christian Rome.