In the earliest times, the Tiber extended between the Palatine and the Aventine, for there the river, as I have already remarked, formed a bay of the sea, and the district between the Tarpeian and the Palatine hills was a marsh, which, when the waters rose high, became a lake: afterwards this place was the _Forum_. The valley between the Palatine and Aventine was always filled with water, independent of inundations, for the river there formed a real bay: this district was called the _Velabrum_. Rome consisted, for the most part, of isolated patches of houses on the hills, for the marsh extended from the Forum to the valley between the Viminal and Esquiline. When you examine the history of the restoration of the city, and inquire as to which district was marshy, you find that even now the place once occupied by the Forum Augusti is called Pantani (marsh). For the purpose of draining this marsh, the Romans built the sewers, which are ascribed to one of the Tarquins—it is uncertain whether to the father or to the son—and which still exist. The intention was to drain the whole of the lower districts between the Palatine, Aventine, Capitoline, Esquiline, and the sea, to facilitate the communication between the several hills, to render the plain fit for agriculture, instead of cultivating only the sides of the hills, and at the same time to make the city inhabitable in regard to fortifications: in like manner London has, within a period of twenty years, become an entirely new city; for many thousands of houses have been bought and pulled down for the purpose of making the streets broader. It was necessary to make an embankment by the river side in order to obtain firm ground behind it, and then to build the great sewers (_cloacae_). We must not conceive these works to be executed according to our dwarfish notions: they were large vaults receiving the waters of the low districts and carrying them into the river; I always feel sorry to be obliged to use an ignoble name for those magnificent works. The marsh then had to be filled up, which is not indeed mentioned by the ancients, but is self-evident. Afterwards, these cloacae were extended at different times, under the Forum as far as the Subura between the Viminal and the Esquiline, so that all those districts were drained by a vast system of sewers. Thus Rome, throughout this extent, was reclaimed as building ground. I shall afterwards have to say something more about these cloacae.