13th-Century Castles — Military Gothic and Concentric Enclosures

The 13th century saw castle-building reach its peak in France. Concentric fortifications — multiple rings of walls reinforcing one another — became the standard, inspired by Byzantine and Crusader castles. Saint Louis and his son Philip III undertook major building programmes, producing monuments such as Carcassonne and Coucy. Siege warfare drove constant architectural innovation: higher towers, wider ditches and increasingly sophisticated gatehouses.