The country on our left is now getting to be more open, and is assuming the appearance of the Campagna; though gardens and a sort of meagre suburbs are still met with. After passing the Porta Pia, which is near the ancient Porta Nomentana, we come to a line of wall that is evidently different from the rest in construction, and even in elevation. It forms three sides of a square, or nearly so, projecting in that form beyond the regular walls of the town, of which, however, it forms a part. This is the enclosure of the Pretorian Camp, though now composing part of the defences of the town. All this part of Rome, within the walls, is in gardens or vineyards, though one can find his way among them on horseback, by means of paths, lanes and breaches. We next approach the gate of San Lorenzo, which leads to Tivoli and the Sabine Hills. Here, half a mile from the walls, stands one of the basilicæ of Rome. It is an ancient church, and is remarkable for the variety and richness of its columns, many of which are of precious African marbles, or of porphyry, and all of which, I believe, are taken from the ruins of ancient Rome. One of the old writers, it is said, speaks of two columns that were made by certain artists, who marked them by a frog and a lizard, animals whose Latin or Greek appellations corresponded with their own, (at least this is the tradition,) and these columns still exist in this church. I can vouch for the columns, but not for the story, which may, nevertheless, be true. The country now opens still more, and just before we reach the gate of Naples, and after passing under the arches of an aqueduct, we will turn upon the Campagna, and gallop across the swells, which are but little enclosed. After proceeding a mile or two, sometimes following roads, and at others coursing over fields that seem as deserted as the ruins with which they are dotted, we reach a small brick edifice, that is said to have been erected on the spot where Coriolanus was met by his mother. There are other accounts of this edifice, which is evidently ancient, though so diminutive and frail-looking; but the brickwork of Rome seems to have a power of endurance that the stone-work of other countries does not possess. Seeing the line of ruined tombs which mark the course of the Appian Way on our right, we will now gallop in that direction. The paths across the fields, the runs of water, and the wildness of scenery, harmonize well with the pictures of antiquity, and our spirits rise with the speed of the horses,—animals, by the way, of great powers of endurance, as well as foot and fire. These horses are derived from barbs, the breed of the Chigi, so called from the princes of that name, is of the best repute; and the horse I ride is noted for his courage, though he has seen near twenty years. This fine beast is as white as snow, and has long been a favourite with the strangers.