bastion - projecting part of a rampart or other fortification

bunker, dugout - a fortification of earth; mostly or entirely below ground

castle - a large building formerly occupied by a ruler and fortified against attack

defensive structure, defense, defence - a structure used for defense; "the artillery battered down the defenses"

defilade - the arrangement of defensive fortifications to protect against enemy fire

entrenchment, intrenchment - an entrenched fortification; a position protected by trenches

escarp, protective embankment, scarp, escarpment - a steep artificial slope in front of a fortification

fieldwork - a temporary fortification built by troops in the field

lunette - temporary fortification like a detached bastion

Maginot Line - a fortification built before World War II to protect France's eastern border; initially considered to be impregnable it was easily overrun by the Germans in 1940

palisade - fortification consisting of a strong fence made of stakes driven into the ground

breastwork, parapet - fortification consisting of a low wall

bulwark, rampart, wall - an embankment built around a space for defensive purposes; "they stormed the ramparts of the city"; "they blew the trumpet and the walls came tumbling down"

Siegfried line - German fortifications facing the Maginot Line

stockade - fortification consisting of a fence made of a line of stout posts set firmly for defense

artistry, prowess, art - a superior skill that you can learn by study and practice and observation; "the art of conversation"; "it's quite an art"

enrichment - act of making fuller or more meaningful or rewarding