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History

Medieval Castle Concentric Defenses

Quick fact

Edward I's Caerphilly Castle and Beaumaris Castle in Wales—both built in the late 13th century—are considered the ultimate expressions of concentric design, featuring not one but multiple concentric rings of walls and water defenses. Their geometry was so effective that they were never successfully taken by storm.

Why this is interesting

Imagine a single wall around a castle: if the enemy breaks through that one wall, their job is done. Now imagine three or four walls, each with its own gate, towers, and defenders. Why would that force the enemy to fight a long, deadly game of 'surround and check'?