Citadel

from WordNet (r) 3.0 (2006)

citadel
    n 1: a stronghold into which people could go for shelter during
         a battle [syn: {bastion}, {citadel}]

from The Collaborative International Dictionary of English v.0.48

Citadel \Cit"a*del\, n. [F. citadelle, It. citadella, di?. of
   citt? city, fr. L. civitas. See {City}.]
   A fortress in or near a fortified city, commanding the city
   and fortifications, and intended as a final point of defense.
   [1913 Webster]

   {Syn}. -- Stronghold. See {Fortress}.
      [1913 Webster]

from Moby Thesaurus II by Grady Ward, 1.0

32 Moby Thesaurus words for "citadel":
      acropolis, bastion, beachhead, blockhouse, bridgehead, bunker,
      castle, donjon, fasthold, fastness, fort, fortress, garrison,
      garrison house, hold, keep, martello, martello tower, mote, motte,
      peel, peel tower, pillbox, post, rath, redoubt, safehold,
      strong point, stronghold, tower, tower of strength, ward

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