Before the development, of large publicly-financed, centralized governments capable of supporting strong national armies, cities were normally left to their own devices for protection. As a result, many civilizations constructed WALLS around their cities to protect against invaders from other regions, or from bandits and pirates. CITY WALLS represented a major investment of resources and required many years to complete. But these WALLS transformed the city into a fortress, capable of withstanding all but the most determined attack.
