the Pomœrium to the Porta Capena, which was the first enlargement of Rome; and that this was partly to drain off the water, and partly for defence. There is too much water there for excavations to be easily made, otherwise the finest antiquities might be found in the Circus: the Obelisk was brought to light from thence in the sixteenth century. The _Agua Marrana_ is not the _aqua damnata_ of Agrippa: in the old Circus there was a canal which carried the water off. Here was the _septem viarum vicus_ where Ancus cut the ditch, perhaps as far as the sewers. Moreover the Roman and the Sabine towns were still separated by the Forum, which was a marsh. The whole neighbourhood of the Velabrum was as yet a river or a lake; and before this was drained, a topical union of the two towns was impossible: the Janus, probably a dyke, was the only road. To effect this, the works were now executed which are ascribed to Tarquinius Priscus, the immense sewers, or more properly, river tunnels, consisting of one main and several minor channels. The main sewer (_cloaca maxima_) of a most ancient style of architecture, may be seen to this day, and still carries off the water. Its width is 18 palms,[80] and it is formed by three stone vaults of _peperino_ (a volcanic stone from Gabii and Alba), one above the other, built in the shape of a semicircle. These form the gigantic work: the stones, each of which is 7½ palms long, and 4⅙ palms broad, are joined by no cement or dovetailing, nor any thing of the kind; they hold together merely from the way in which they fit, and the exact closing of the arch. The structure has not for two thousand years undergone the slightest change, having stood unshaken the shock of earthquakes, which have laid waste the rest of the city, and overthrown obelisks; so that one might say that it will see the end of the world. This is the work which made it possible to form Rome into a whole of that extent which it afterwards had. The entire embankment of the river, the quay, is likewise built of stone, of the volcanic stone from Alba; and we may recognise there also the same style of architecture. The other vaults begin between the Quirinal and the Viminal, and run beneath the Forum Augustum, the Forum Romanum and the Forum Boarium into the Velabrum and the _cloaca maxima_. They are of equally perfect preservation; but they lie deep under ground. They were found during the papacy of Benedict XIV. They are executed on the same immense scale; but they are built of _travertino_, from which it is manifest, that they are of a later age, and yet perhaps of the time of the republic, somewhat about the first half of the fifth century, before the war of Hannibal. Now therefore the whole country as far as the river was inhabitable, even beyond the Capitoline hill. Soon, however, were greater plans devised for the enlargement of the city. On the north side of the Esquiline, where the kings had built a rampart, level space was to be secured which had