|Part of Themistocles's wall in Kerameikos|
In the Early Iron Age of the eleventh and tenth centuries BCE, Greek settlements were unwalled. But in subsequent centuries, along with developing forms of social organization that prompted effective mobilization of soldiers, Greek poleis increasingly invested in substantial fortifications: urban circuits, and later in long walls connecting cities to harbors, and forts and towers to protect rural populations and assets. The preference for strong walls was not universal: Sparta remained unwalled throughout the classical period, believing that “our men are our walls.” Some Greek political theorists, notably Plato in the Republic, argued against walling the city on the grounds that brave men ought willingly to fight their enemies in the open field. But by the end of the classical period, this was a minority position: Aristotle thought it badly outdated. Fortification policy was one way in which Greek poleis became more similar to one another over time.
Fortification walls were costly… Yet the no-wall option clearly became less attractive over time, as Greek poleis grew wealthier. Fortifications figured in early stages of Greek state formation and, from the early fifth century BCE to the fourth century, more Greek cities were increasingly heavily fortified. Late classical city walls were on the whole more substantial (built of stone, rather than mud-brick), more highly developed (towers, crenellations, indented trace), and in many cases augmented with outworks and elaborate systems of rural defense (forts, watchtowers, pass-control walls).