The stretch of the Aurelian Walls extending from Porta Asinaria to Porta Latina is over three kilometers long and has been partially modified by later interventions, which have altered its readability. Between the 16th and 18th centuries, the reshaping of the urban layout of the area between the basilicas of S. Giovanni in Laterano and S. Croce in Gerusalemme also modified the topography, partially obliterating a section of the Walls that was rediscovered in the 2000s during the construction works for Metro C. Modern urbanization has further contributed to partially concealing the route of the ancient fortification.
Porta Asinaria was originally built over the eponymous road, a secondary route compared to the more important Via Latina and Via Appia. Beyond it, the Walls run along the slope of the Lateran Hill, which originally descended steeply toward the Walls. In 1574, it was decommissioned and replaced by Porta San Giovanni, located at a higher elevation, consistent with the natural and anthropogenic rise of the ground.
Heading west, the exterior side of the Walls overlooks the gardens of Via Sannio, while near Via Locri it is hidden by a private residence, Villa Elika. In this area, the Aurelian Walls mark the boundary between the Italian State and the Vatican City. Hidden between Villa Elika and the garden of the Pontifical Roman Seminary (Piazza S. Giovanni in Laterano, no. 4) is a small gate, the so-called Posterula Lateranense, which served as a secondary passage through the Walls. The defensive circuit continues through the area of the Società Sportiva Romulea and, after crossing the intersection of Piazzale Ipponio and Via dei Laterani, resumes along Via della Ferratella up to Porta Metronia, bordering the Tennis Roma club.
Between Porta Metronia and Porta Latina, the Aurelian Walls, with 19 towers regularly spaced at 30 meters apart, follow a slightly undulating course toward the southwest, enclosing the extensions of the Celio and Aventine Hills. Porta Metronia was built in a recess of the Valle delle Camene to allow access to the Celio. Without towers on its sides, it was protected by the Walls themselves, and only later was a projecting tower added on the city side, functioning as a counter-gate. In 1122, it was walled up and closed, since during the papacy of Callixtus II, the Aqua Mariana canal was directed through it.
Architecturally, the Walls are mostly from the Honorian phase. The towers have square plans with two floors connected by a staircase, with two or three arched windows on the inner side; they are linked by a covered walkway, with arrow slits for archers, modified in the 19th century for firearms. On the exterior, the green layout of the Linear Park allows full appreciation of their beauty and height, and of the wall palimpsest, the result of countless restoration interventions. On the interior side, long stretches had been covered by fill, reaching heights of about six meters in some areas, accumulated from the 16th century until the late 1970s, when the restorations by the Municipality of Rome recovered them.