The existence of infectious diseases specialists in Ancient Rome is unlikely, but there were at least three authors able of keen observations on infectious matters, with enough merit to be considered our predecessors: Varro, Columella and Vitruvius, none of them physicians. Varro, in his first Book on Agriculture recommended, "Build the houses distant from swamps, because certain minute creatures are bred which cannot be followed with the eyes but which float in the air and enter the body through the mouth and nose, giving rise to severe diseases". Also in a text of agriculture and in the same sense, Columella says "that with heat a swamp releases a pestilential vapor and produces a very dense swarm of insects, which come flying over us armed with harmful stings Vitruvius, the great architect was worried about drinkable water: its sources and properties, how to obtain it and the methods for testing its quality. The concern on its distribution and disposal of sewage started on 614 B.C., little after the foundation of Rome, with the building of the first aqueduct, the Aqua Marcia. This aqueduct in Trajan's times (century II A.D.), reached a total of 443 km, with 49,500 meters of arcades, which were up to 32 meters high, plus 2.4 km of an underground net. This system released 947,200 m(3) of water per day, two thirds of which were for public use and one third for private customers.