From this source sprang the elaborate system of fortifications, with walls, ramparts, towers, canals, ditches, that continued to characterize the chief historic cities, apart from certain special cases—as during the Pax Romana—down to the eighteenth century.
Dende esta fonte apareceu o elaborado sistema de fortificacións, con paredes, murallas, torres, canais, gabias, que continuaron a caracterizar as cidades históricas, á parte de certos casos especiais -como durante a Pax Romana- ata o século XVIII.