At the western corner of the Arch of Severus are the scanty remains of a tall conical pyramid, about fifteen feet in diameter, which is identified as the Umbilicus Romæ, placed in the exact centre of old Rome. Not far from it stood the Milliarium Aureum, or Golden Milestone, on which were inscribed all the distances of roads without the walls. The Roman roads throughout the empire terminated at this point. With this central milestone was connected that admirable system of roads which the Romans constructed in our distant island; and it is a remarkable circumstance that the principal railway lines in England are identical with the general direction of the old Roman roads. The Antonine Way is now the Great Western Railway, and the Roman Watling Street, which ran diagonally across the country from Chester in the north-west to Dover in the south-east, is now replaced by the Dover, London, Birmingham, Grand Junction, Chester, and Crewe Railways. The reason of this union of ancient and modern lines of communication is obvious. The Romans formed their roads for the purpose of transporting their armies from place to place, and at certain distances along the roads a series of military stations were established. In course of time these stations became villages, towns, and cities such as Chester, Leicester, Lancaster, Manchester. Thus, strange as it may appear, the Milliarium Aureum of the Roman Forum has had much to do with the origin of our most ancient and important towns, and with the formation of the great lines of railway that now carry on the enormous traffic between them.

The exposed vaults immediately behind the Arch of Severus, bounding the Forum in this direction, are richly draped with the long, delicate fronds of the maidenhair fern. Shaded from the sun, it grows here in the crevices of the old walls in greater luxuriance and profusion than elsewhere in the city. There is something almost pathetic in this association of the frailest of Nature's productions with the ruins of the most enduring of man's works. Strength that is crumbling to dust and ashes, and tender beauty that ever clings to the skirts of time, as she steps over the sepulchres of power, have here in their combination a deep significance. The growth of the soft fern on the mouldering old stones seems like the sad, sweet smile of Nature over a decay with which she sympathises, but which she cannot share. The same feeling took possession of me when, wandering over the ruins of the Palaces of the Cæsars on a sunny February afternoon, I saw above the hoary masses of stone the rose-tinted bloom of almond-trees. Out of the gray relics of man's highest hour of pride, the leafless almond-rod blossomed as of old in the holy place of the Hebrew Tabernacle; and its miracle of colour and tenderness was like the crimson glow that lingers at sunset upon Alpine heights, telling of a glory that had long vanished from the spot.

Beneath these fern-draped vaults is the oldest prison in the world. The celebrated Mamertine Prison takes us back to the very foundation of the city. It was regarded in the time of the Cæsars as one of the most ancient relics of Rome, and was invested with peculiar interest because of its venerable associations. It consists of a series of vaults excavated out of the solid tufa rock, where it slopes down from the Capitoline Hill into the Forum, each lined with massive blocks of red volcanic stone. For a long time these vaults have been used as cellars under a row of tall squalid-looking houses built over them between the Via di Marforio and the Vicolo del Ghettarello; and the sense of smell gives convincing proof that where prisoners of state used to be confined, provisions of wine, cheese, and oil have been stored. The prison has recently passed into the possession of the British and American Archæological Society of Rome, which pays a certain rent to the Italian Government for its use. By this society it is illuminated and shown every Monday afternoon during the season. One of the members conducts the party through the upper and lower prisons, and explains everything of interest connected with them. Dr. Parker, whose labours have done so much to elucidate this part of ancient Rome, was the guide on the occasion of my visit; and as the party was unusually small, we had a better opportunity of seeing what was to be seen, and hearing the guide's observations.