The Roman Walls of Lugo are the only complete and intact urban defensive walls surviving anywhere in the former Roman Empire.
Their circumference is 2.117 km. Five of the original gates, and 46 interval towers are still intact.
Lugo was called Lucus Augusti by the Romans. This regionally important colonial town was founded in 15-13 BCE. The walls however were only constructed between 263 and 276, when the fear for invasions became too high. The fortifications couldn’t withstand outsiders for too long: Lugo was subsequently sacked by the Suevi, the Visigoths, the Moors and the Normans from the 5th century on.
Source: www.worldheritagesite.org
Photo: whc.unesco.org