The Aurelian Walls were built between 270 and 275 by the Emperor Aurelian to defend Rome against attacks of the Barbarians people. After undergoing many renovations in later times, both in antiquity and in modern times, the walls appear today in good condition for most of their route. In ancient ran for about 19 km, today are long 12.5 km. At the beginning of the fifth century, with the arrival of Alaric's Goths, were settled the action more incisive on the Walls, operated by the Emperor Honorius: their height was almost doubled by creating a discovered double walkway, surrounded by battlements. Even the towers were reinforced with a second floor and many doors were restored. The Walls continued to have a defensive role for the city for centuries, until 1870 when, with the Socket of Rome, the Sharpshooters opened a breach near Porta Pia and put an end to the time domain of the papacy. Just to their long functionality is the good state of preservation, which is now dedicated the Museum of the Walls, near Porta St. Sebastiano.