Although the darkness was prolonged and intense before the dawn of medical science in Rome, yet, in ancient times, there was a considerable amount of knowledge of sanitation. The great sewer of Rome, the _Cloaca Maxima_, which drained the swampy valley between the Capitoline and Palatine Hills, was built by order of Tarquinius Priscus in 616 B.C. It is wonderful that at the present time the visitor may see this ancient work in the Roman Forum, and trace its course to the Tiber. In the Forum, too, to the left of the Temple of Castor, is the sacred district of Juturna, the nymph of the healing springs which well up at the base of the Palatine Hill. _Lacus Juturnæ_ is a four-sided basin with a pillar in the middle, on which rested a marble altar decorated with figures in relief. Beside the basin are rooms for religious purposes. These rooms are adorned with the gods of healing, Æsculapius with an acolyte holding a cock, the Dioscuri and their horses, the head of Serapis, and a headless statue of Apollo. The Cloaca Maxima was formed of three tiers of arches, the vault within the innermost tier being 14 ft. in diameter. The administration of the sewers, in the time of the Republic, was in the hands of the censors, but special officers called _curatores cloacarum_ were employed during the Empire, and the workmen who repaired and cleansed the sewers were condemned criminals. These ancient sewers, which have existed for twenty-five centuries, are monuments to the wisdom and power of the people who built them. In the time of Furius Camillus private drains were connected with the public sewers which were flushed by aqueduct and rain water. This system has prevailed throughout the centuries. The Aqueducts were also marvellous works, and although they were added to in the time of the Empire, Sextus Julius Frontinus, curator of waters in the year A.D. 94, gives descriptions of the nine ancient aqueducts, some of which were constructed long before the Empire. For instance, the _Aqua Appia_ was conducted into the city three hundred and twelve years before the advent of Christ, and was about seven miles long. The _Aqua Anio Vetus_, sixty-two miles in length, built in B.C. 144, was conveyed across the Campagna from a source in the country beyond Tivoli. Near this place there is a spring of milky-looking water containing sulphurous acid, sulphurated lime, and bicarbonate of lime, used now, and in ancient times for the relief of skin complaints. This water, at the present day, has an almost constant temperature of 75°.