A fortified tower (also defensive tower or castle tower or, in context, just tower) is one of the defensive structures used in
fortification A fortification is a military construction or building designed for the defense of territories in warfare, and is also used to establish rule in a region during peacetime. The term is derived from Latin ''fortis'' ("strong") and ''facere'' ( ...

s, such as
castle A castle is a type of fortification, fortified structure built during the Middle Ages predominantly by the nobility or royalty and by Military order (monastic society), military orders. Scholars debate the scope of the word ''castle'', but u ...

s, along with
curtain wall Curtain wall may refer to: * Curtain wall (architecture), the outer skin of a modern building * Curtain wall (fortification), the outer wall of a castle or defensive wall between two bastions