Resuming our course along the Appian Way, we passed the tomb of the Scipios; and, making our exit by the Sebastian gate, we came, after a ride of two miles in the open country, to the basilica of San Sebastiano, erected over the entrance to the Catacombs. Pulling a bell which hung in the vestibule, a monk appeared as our cicerone, and we might have been pardoned a little misgiving in committing ourselves to such a guide through the bowels of the earth. His cloak was old and tattered, his face was scourged with scorbutic disease, misery or flagellation had worn him to the bone, and his restless eye cast uneasy glances on all around. He carried in his hand a little bundle of tallow candles, as thin and worn as himself almost; and, having lighted them, he gave one to each of us, and bade us follow. We descended with him into the doubtful night. The place was a long shaft or corridor, dug out of the brown tuffo rock, with the roof about two feet overhead, and the breadth two thirds or so of the height. The descent was easy, the turnings frequent, and light there was none, save the glimmerings of our slender tapers. The origin of the Catacombs is still a disputed question; but the most probable opinion is, that they were formed by digging out the pozzolana or volcanic earth, which was used as a cement in the great buildings of Rome. They extend in a zone round the city, and form a labyrinth of subterranean galleries, which traverse the Campagna, reaching, according to some, to the shore of the Mediterranean. He who adventures into them without a guide is infallibly lost. They speak at Rome of a professor and his students, to the number of sixty, who entered the Catacombs fifty years ago, and have not yet returned. Certain it is, that many melancholy accidents have occurred in them, which have induced the Government to wall them up to a certain extent. I had not gone many yards till I felt that I was entirely at the mercy of the monk, and that, should he play me false, I must remain where I was till doomsday.