We pass now over two centuries and a half.  About five years ago the Cavaliere de Rossi found lying upon the ground, in a vigna bordering on the Appian Way, about two miles from Rome, a portion of a sepulchral stone on which were the letters NELIUS MARTYR, the NE broken across.  He immediately conjectured that this was a piece of the stone that had covered the grave of Pope Cornelius, [A.D. 250-252,] and on the truth of this conjecture important results depended.  It was known that this pope had been buried in the Catacombs of St. Callixtus; and it was known also, from the itineraries and some other sources, that his grave was not in the same chamber with the graves of the other popes who were buried in those catacombs, but that it was not far away from it.  It was further known, as we have seen, that the chapel in which St. Cecilia had been buried was close to the Chamber of the Popes.  But a tradition dating from a late period of the Middle Ages had given the name of Callixtus to the catacombs opening from the Church of St. Sebastian, at a little greater distance from Rome.  In these catacombs the place supposed to be that of St. Cecilia’s grave was pointed out, and an inscription set up to mark the spot, by a French archbishop, in the year 1409, still exists.  Many indications, however, led De Rossi to disbelieve this tradition and to distrust this authority.  It contradicted the brief indications of the itineraries, and could not be reconciled with other established facts.  Not far from the place where the broken inscription was found was an accidental entrance into catacombs which had been supposed to have been originally connected with those of St. Sebastian, but were believed by De Rossi to be a portion of the veritable Catacombs of St. Callixtus, and quite separate from the former.  The paths in this part, however, were stopped up in so many directions, that it was impossible to get an entrance through them to such parts as might determine the question.  Again, in the neighborhood of the discovery of the broken stone was an old building, used as a stable, and for other mean purposes.  On examination of it, De Rossi satisfied himself that it had been originally one of the churches erected in the fourth century at the entrance of the catacombs, and he had little doubt that he had now found the place of the main descent into the Catacombs of St. Callixtus.  The discovery was a great one; for near the main entrance had been the burial-place of the popes, and of St. Cecilia.  De Rossi laid the results of his inductive process of archaeological reasoning before the pope, who immediately gave orders for the purchase of the vigna, and directions that excavations should be at once begun.[N]