The section of fortifications between Porta Labicana and Porta Prenestina (Porta Maggiore) and Porta Asinaria is approximately 1.2 km long.
After passing Piazzale Labicano, the Walls form an almost right angle and run southeast along the route of the Aqua Claudia aqueduct, following the line of modern Via Casilina. At the intersection with the Tangenziale Est, they turn southwest along Viale Castrense, following a straight and level path except for the sloped section, which follows a natural depression and provides a backdrop to the gardens of Viale Carlo Felice, a large green area designed by architect Raffaele De Vico in the early 20th century with a system of multi-level paths reaching the level of the ancient pavement.
The route was interrupted in 1575 with the construction of Porta San Giovanni, which became the new entrance to the Basilica of St. John Lateran after Porta Asinaria, partially buried, was abandoned. In the early decades of the 20th century, additional vehicular and pedestrian passages were created following the urbanization of the Appio-Latino district. This area, originally outside the city, retained a rural character until the late 19th and early 20th centuries, when the first urban plans defined building plots, mostly intended for the bureaucratic population of the new Capital.
Within the city, the Walls, which for a long stretch run along the pillars of the pre-existing Aqua Claudia and Anio Novus aqueducts, connect two important religious centers, the Basilicas of St. John Lateran and Santa Croce in Gerusalemme, along a route once also used as a “processional itinerary.”
The external façade of the Walls in this section is visible for a short stretch on Via Casilina, while the corresponding internal side can be visited within the Santa Croce in Gerusalemme complex for about 400 meters, where it leans against the pillars of the Aqua Claudia. From Viale Castrense to Porta Asinaria, both sides of the Walls are accessible and preserved to a considerable height, largely attributable to the Honorian phase. In this sector, innovative architectural solutions can be seen, such as the construction of a double overlapping gallery for a stretch of more than 100 meters between Porta San Giovanni and the Castrense Amphitheatre, a performance building that was part of a Severan-era imperial residence and later integrated into the defensive circuit as a fortress.