Aqua Claudia
Aqua Claudia was an aqueduct of ancient Rome that, like the Anio Novus , was begun by emperor Caligula in 38 AD and completed by Claudius in 52 . Its main springs, the Caeruleus and Curtius, were situated 300 paces to the left of the thirty-eighth milestone of the Via Sublacensis . After being in use for ten years, the supply failed, and was interrupted for nine years, until Vespasian restored it in 71, and ten years later Titus once more.

The channel length was 45–46 miles (ca. 69 km, most of which was underground) in different times and volume at the springs was 191,190 cubic metres in 24 hours. After building the Arcus Neroniani by Nero, one of the branches of the Aqua Claudia, the aqueduct could provide all 14 Roman districts with water. Directly after its filtering tank, near the seventh mile of the Via Latina , it finally emerged onto arches, which increase in height as the ground falls towards the city. It is also one of the two ancient aqueducts that flowed through the Porta Maggiore, the other being the Anio Novus. It is described in some detail by Frontinus in his work published in the later first century, De aquaeductu.