by Giuseppe Agostino Pietro Vasi, 1747

Porta Maggiore, or Porta Prenestina, is one of the eastern gates of the ancient but well-preserved 3rd-century Aurelian Walls of Rome. Two ancient roads ran through the gate: the Via Praenestina and the Via Labicana. The Via Prenestina was the eastern road leading to the ancient city of Praeneste (present-day Palestrina). The Via Labicana (now called Via Casilina) heads south-east of the city.

The "gate", built in AD 52 by the emperor Claudius, was originally meant to provide a decorative supporting section for two aqueducts, the Aqua Claudia and the Anio Novus. At that time these aqueducts crossed the ancient Via Labicana and Via Praenestina, thus offering the opportunity to create here a kind of triumphal arch to the conquest of nature and to its conqueror, the emperor Claudius. The two channels of these aqueducts (the Aqua Claudia and the Aqua Anio Novus), one above the other, can be seen by looking at the cross-section