How do castles defend against attackers?

Medieval castles were built as fortified residences and military strongholds. High stone walls, battlements, arrow slits, and gatehouses gave defenders cover and visibility. Moats and drawbridges made it harder for enemies to reach the walls, while towers allowed defenders to fire from multiple angles. Many castles also controlled roads, rivers, or strategic high ground, which gave their owners political power as well as military protection. Famous examples include the Tower of London and Krak des Chevaliers in Syria, both of which show how architecture was used for defense.