The scenery for a time continues to improve. The oak woods become higher, the inland hills are more varied in outline and are forest-clad. Here peeps out a crag, there a village or a castle. At Palo a large, unattractive villa and a picturesque old castle overlook a fine line of sea-beach, where the less wealthy classes in Rome come down for a breath of fresh air in the hot days of summer. It also marks the site of Alsium, where, in Roman times, one or two personages of note, of whom Pompey was the most important, had country residences. For a time there is no more level plain; the land everywhere shelves gently to the sea, covered with wood or with coarse herbage. But before long there is another change, and the great plain of the Tiber opens out before our eyes, extending on one hand to the not distant sea, on the other to the hills of Rome. It is flat, dreary, and unattractive, at any rate in the winter season, as is the valley of the Nen below Peterborough, or of the Witham beyond the Lincolnshire wolds. It is cut up by dykes, which are bordered by low banks. Here and there herds of mouse-colored oxen with long horns are feeding, and hay-ricks, round with low conical tops, are features more conspicuous than cottages. The Tiber winds on its serpentine course through this fenland plain, a muddy stream, which it was complimentary for the Romans to designate _flavus_, unless that word meant a color anything but attractive. One low tower in the distance marks the site of Porto, another that of Ostia and near the latter a long grove of pines is a welcome variation to the monotony of the landscape. These two towns have had their day of greatness. The former, as its name implies, was once the port of Rome, and in the early days of Christianity was a place of note. It was founded by Trajan, in the neighborhood of a harbor constructed by Claudius; for this, like that of Ostia, which it was designed to replace, was already becoming choked up. But though emperors may propose, a river disposes, especially when its mud is in question. The port of Trajan has long since met with the same fate; it is now only a shallow basin two miles from the sea. Of late years considerable excavations have been made at Porto on the estate of Prince Tortonia, to whom the whole site belongs. The port constructed by Trajan was hexagonal in form; it was surrounded by warehouses and communicated with the sea by a canal. Between it and the outer or Claudian port a palace was built for the emperor, and the remains of the wall erected by Constantine to protect the harbor on the side of the land can still be seen. The only mediæval antiquities which Porto contains are the old castle, which serves as the episcopal palace, and the flower of the church of Santa Rufina, which is at least as old as the tenth century.