Wonder has been manifested at the behavior of Constantine towards S. Paul, whose basilica at the second milestone of the Via Ostiensis appears like a pigmy structure in comparison to that of S. Peter. Constantine had no intention of placing S. Paul in an inferior rank, or of showing less honor to his memory. He was compelled by local circumstances to raise a much smaller building to this apostle. As before stated, there were three rules which builders of sacred memorial edifices had to observe: first, that the tomb-altar of the saint in whose honor the building was to be erected should not be molested or moved from its original place either vertically or horizontally; second, that the edifice should be adapted to the tomb so as to give it a place of honor in the centre of the apse; third, that the apse and the front of the edifice should look towards the east. The position of S. Peter's tomb in relation to the circus of Nero and the cliffs of the Vatican was such as to give the builders of the basilica perfect freedom to extend it in all directions, especially lengthwise. This was not the case with that of S. Paul, which was only a hundred feet distant from an obstacle which could not be overcome,--the high-road to Ostia, the channel by which the city of Rome was fed. The road to Ostia ran _east_ of the grave; hence the necessity of limiting the size of the church within these two points. Discoveries made in 1834, when the foundations of the present apse were strengthened, and again in 1850, when the foundations of the baldacchino of Pius IX. were laid,[87] have enabled Signor Paolo Belloni, the architect, to reconstruct the plan of the original building of Constantine. His memoir[88] is full of useful information well illustrated. One of his illustrations, representing the comparative plans of the original and modern churches, is here reproduced. The plan needs no comment, but one particular cannot be omitted. In the course of the excavations for the baldacchino, the remains of classical columbaria were found a few feet from the grave of the apostle, with their inscriptions still in place. He must, therefore, have been buried, like S. Peter, in a private area, surrounded by pagan tombs. In 386 Valentinian, Theodosius, and Arcadius asked Flavius Sallustius, prefect of the city, to submit to the Senate and the people a scheme for the reconstruction _a fundamentis_ of the basilica, so as to make it equal in size and beauty to that of the Vatican. To fulfil this project, without disturbing either the grave of the apostle or the road to Ostia, there was but one thing to do; this was to change the orientation of the church from east to west, and extend it at pleasure towards the bank of the Tiber. The consent of the S. P. Q. R. was easily obtained, and the magnificent temple, which lasted until the fire of July 15, 1823, was thus raised so as to face in a direction opposite to the usual one.