Porta San Sebastiano

The largest and best-preserved gate of the Aurelian Walls (3rd century AD), and the starting point of the ancient Appian Way. The gate also houses the small Museo delle Mura, where you can climb up and walk a preserved section of the wall itself for about 350 metres — one of the few places in Rome where you can experience the scale of the city's ancient defenses from the parapet. Closed Mondays; very rarely crowded.