Martello Tower

(n.) A building of masonry, generally circular, usually erected on the seacoast, with a gun on the summit mounted on a traversing platform, so as to be fired in any direction.

Thesaurus Entries

bastion, beachhead, blockhouse, bridgehead, bunker, castle, citadel, donjon, fasthold, fastness, fort, fortress, garrison, garrison house, hold, keep, martello, martello tower, mote, motte, peel, peel tower, pillbox, post, rath, safehold, strong point, stronghold, tower, tower of strength, ward