The Aurelian Walls are the late-Roman fortifications that once enclosed the imperial city of Rome, Italy, built under Emperor Aurelian in the late third century AD when the capital could no longer rely solely on its legions for protection. Stretching for nearly 19 kilometers in their original circuit, the brick-faced walls incorporated existing structures — such as aqueducts, warehouses, and even amphitheaters — into a continuous defensive line. Their towers, gates, and long stretches of masonry still rise across modern neighborhoods, offering one of the most visible reminders of Rome's transformation from imperial metropolis to fortified late-antique city. The best-preserved sections of the Aurelian Walls are located near Porta San Sebastiano, Porta Maggiore, Porta Pia and the Testaccio area. The impressive Porta San Sebastiano also houses the Museum of the Walls, Museo delle Mura. - AsNotedIn