castle Synonym

fortress - palace - stronghold - citadel - keep - manor - chateau - fort - bastion - tower - donjon - redoubt - fastness - hold - mansion - estate - residence - seat - hall - villa - lodge - abbey - monastery - convent - priory - cloister - retreat - sanctuary - refuge - asylum - haven - safehouse - bulwark - blockhouse - acropolis - alcazar - burg - schloss - zamek - castello - castillo - château - palais - palazzo - palac

A castle is a large fortified building or set of buildings, often with high walls, towers, and sometimes moats, built in the past by knights or noble families to protect against invasions. Castles were central to military defense during the medieval period and also served as residences, administrative centers, and symbols of power.