Synonyms and related words :
acropolis, advance guard, airhead, avant-garde, bastion, battle line, beachhead, blockhouse, bunker, castle, citadel, donjon, farthest outpost, fasthold, fastness, first line, forefront, fort, fortress, front, front line, front rank, front-runner, garrison, garrison house, hold, keep, line, martello, martello tower, mote, motte, outguard, outpost, peel, peel tower, pillbox, pioneer, point, post, precursor, railhead, rath, safehold, scout, spearhead, strong point, stronghold, tower, tower of strength, van, vanguard, ward,