The cunning reason the ancient city of Sparta did not have any walls

Sparta's society worked very differently from other Greek city-states. 

Reforms linked to a man called Lycurgus, around the 7th century BC, changed the army and the way the community was organised. 

The Spartiates, or full citizens, were a warrior class raised from birth to be soldiers, and the agoge, the strict training and education system, taught them endurance, self-sufficiency, and fighting ability. 

In this setting, relying on walls for protection went against Spartan values, because they believed a city was defended by its people, not by bricks or stone.

The land around Sparta also helped explain why they had no walls, for Sparta sat on the Eurotas River plain surrounded by mountains and natural barriers. 

The Taygetus and Parnon mountain ranges acted as natural defences, reducing the need for walls. 

The land itself gave the Spartans an advantage that allowed them to use the terrain in any defence. 

The Spartan military was at the centre of its defence, and the hoplite phalanx, a formation of heavily armed foot soldiers, was the main part of their forces. 

Armed with 8-foot spears and round shields, the hoplites stood in tight ranks that were nearly impossible to break through. 

Because of that reputation, the Spartans were so well known as fighters that news of their approach often discouraged enemies. 

Their military reputation was so strong that other Greek states looked to them for leadership, especially during the Greco-Persian Wars; for example, the Battle of Thermopylae in 480 BC, though a defeat, showed Spartan determination and their skill in causing heavy losses to a larger army.

The political situation of the time also affected Sparta's choice to stay without walls. 

During the Classical period, Sparta fought often with neighbours and other Greek city-states, most notably Athens in the Peloponnesian War, and having no walls was a bold statement of confidence and a direct challenge to rivals. 

It showed their strength and fearlessness, which was important to Spartan identity and their relations with other states.

The Spartan focus on the military had its problems, as times changed and military technology advanced, making reliance on hoplite warfare less effective. 

The Macedonians under Philip II and his son Alexander the Great introduced a new era of warfare, where the phalanx was just one part of varied and flexible military forces. 

The Theban general Epaminondas also showed the weaknesses of the Spartan system at the Battle of Leuctra in 371 BC, where he used new tactics to defeat the Spartan army.

With their unbeatable reputation gone and facing other challenges at home, Sparta began to lose power and influence over the next century. 

Although their approach worked well during their peak, more losses and fear of future attacks finally made them change, and excavations have shown that Sparta finally faced reality and built defensive walls around 184 BC.