12th-Century Castles — The Heyday of the Cylindrical Keep

The 12th century represented a revolution in French castle architecture. The cylindrical keep established itself as the dominant form, offering better resistance to missiles and siege techniques. The Crusades brought back Eastern methods that enriched the art of fortification. Castles became genuine defensive complexes with successive enclosures, flanking towers and moats. It was also the era of great builder-lords such as Richard the Lionheart, whose Château Gaillard embodies the military genius of the century.