The city wall of Rome, by Aurelian in ad 271–275 in anticipation of a sudden barbarian inroad. The original wall, about 6.5 m. (21 ft.) high to the battlements, extended for 18.8 km. (11½ mi.) with 381 projecting rectangular towers at intervals of 100 Roman ft. (29.6 m.; 32⅓ yds.), except along the river. The wall was usually solid, but in places had an internal gallery or was treated as a revetment. It incorporated many earlier structures, such as the camp of the Praetorian Guard, and the tomb of Cestius. It enclosed most of the fourteen regions (see regio) but only a small part of Trastevere. The seventeen gates, mostly named from the principal roads, were flanked by simple semicircular towers. There were also at least six postern gates. The wall was thus designed to repel a raid rather than stand siege.
Subjects: Classical Studies.