Great Structures - Castles: private fortresses and centers of medieval power

Built predominantly by nobility, royalty, and military orders during the Middle Ages, castles served as private fortified residences. Originating in Europe during the ninth and tenth centuries after the fall of the Carolingian Empire, they provided bases for raids, protection from enemies, and centers of administration. Initially constructed using earth and timber, they evolved to feature stone walls, concentric defenses, and arrowslits. The rise of powerful artillery in the fifteenth century eventually caused true castles to decline, making them uncomfortable residences and leading to their replacement by star forts.

Source: Wikipedia