A "Donjon" is a type of fortified tower that served as the main stronghold within a medieval castle. It was typically the residence of the lord and provided protection during attacks. The design often included thick stone walls, narrow windows, and multiple levels, making it a secure place for defense and living. In addition to its defensive role, the donjon also functioned as a symbol of power and authority. It was often the tallest structure in the castle, representing the lord's dominance over the surrounding land. Many famous castles, such as Château de Fougères in France, feature impressive donjons.