The Aurelian Walls are a line of city walls built between 271 AD and 275 AD in Rome, Italy, during the reign of the Roman Emperor Aurelian. They superseded the earlier Servian Wall built during the 4th century BC. The walls enclosed all the seven hills of Rome plus the Campus Martius and, on the right bank of the Tiber, the Trastevere district. The river banks within the city limits appear to have been left unfortified, although they were fortified along the Campus Martius.