Having thus rapidly passed over the hills, I shall now proceed further. A _suburb_ was first formed between the Palatine, Aventine, and Esquiline on the one side, and the Tiber on the other. I have already mentioned as a part of it the _Forum olitorium_, which was at the same time a fish-market, and still exists unchanged. The suburb became a thickly inhabited district, and in it Augustus built the theatre of Marcellus and the great portico of his sister Octavia. Another suburb extended along the Tiber as far as Ponte Sisto at the great reach of the river, where the amphitheatre of Statilius Taurus was situated; it occupied the whole side of the river, which in our maps is erroneously called Campus Martius. We generally imagine that this Campus was the only one the Romans had; but this is a mistake, for Campi also existed in front of other hills and gates; and like the great Campus, they were gradually covered with houses, though they were neither as extensive nor as important as the Campus Martius. One of them was the _Campus Esquilinus_, in the plain before the Esquiline beyond the agger, and the _Campus Caelimontanus_ at the foot of the Caelius (now the palace of the Lateran) was another. These two Campi are as clear as possible, and are frequently mentioned; their destination was the same as that of the Campus Martius, and when in consequence of inundations the games could not be held in the latter, they were transferred to the Caelimontanus or the Esquilinus. Both these Campi were national property. Ever since the time of Augustus, houses were built in the Campus Martius. It contained the well known _septa_, a place fenced round, in which the centuries voted; even Pompey had built his theatre on the very border of the Campus; Agrippa erected his thermae there, and his incomparably more beautiful Pantheon; and Augustus had there his Mausoleum, from which an avenue of trees led to the buildings of Agrippa. Alexander Severus built there new thermae, a circus, and several triumphal arches, so that the Campus Martius entirely disappeared. In the second and third century Rome extended more and more in that direction, whence at present that part is thickly covered with houses. Of the buildings which are found there, I have already mentioned the thermae of Alexander Severus, the Circus Agonalis, and the structures of Agrippa, and I shall now say a few words about the _Mausoleum, of Augustus_. This building formed a gigantic mass, and was as imperishable as the pyramids. The descriptions we have of it are very obscure, nor do its remains enable us to form an idea of it; the drawings of its remains, which were made in the sixteenth century, are very doubtful. A large bas-relief may still have existed, also a water basin made of stone, which has disappeared in an unaccountable manner; but otherwise I believe that the drawings contain restorations. It is said that there was also a kind of suspended gardens with the