Rome - Porta San Sebastiano (formerly Porta Appia)

This gate in the Aurelian Walls was refortified at the end of the A.D. fourth century in view of the increasing threat to Rome from the Germanic tribes, and was again renovated in the sixth century by Belisarius and Narses. The Porta Appia, later renamed after the church of San Sebastiano outside the city on the Via Appia, was the principal entrance to the ancient city.

The so-called Arch of Drusus (Arco di Druso) inside the Porta San Sebastiano probably dates from the time of Trajan; in the reign of Caracalla it was used to support an aqueduct.
The museum of The Walls of Rome traces the development and history of the walls.