Porta San Sebastiano is the modern name for the ancient Porta Appia, a gate in the Aurelian Wall of Rome, through which the Via Appia, now the Via di Porta San Sebastiano at that location, left the city in a southeasterly direction. It was refortified at the end of the 4th century and was again renovated in the sixth century by Belisarius and Narses. The gate, a brick structure with turrets, still stands and has been restored to good condition. Modern traffic flows under it. Inside and upstairs is a museum dedicated to the construction of the walls and their recent restoration.
The gate is next to the Arch of Drusus.