| citadel(noun, keep, support, structure, defense) |
| fortress(noun, support, hold, cover, keep) |
| fastness(noun, hold, cover, keep, position) |
| keep(noun, hold, defense, refuge, fortification) |
| dungeon(noun, defense, prison) |
| haven |
| bulwark(noun, support, cover, position, guard) |
| bastion(noun, support, place, cover, position) |
| fortification(noun, support, hold, cover, keep) |
| castle(noun, keep, defense, refuge, fortification) |
| cell(noun, fortification, presidio, prison, sustainment) |
| fort(noun, hold, cover, keep, position) |
| garrison(noun, cover, position, guard, shield) |
| base complex(significance, facility, army) |
| defense(noun, support, cover, guard, resistance) |
| donjon(noun, hold, keep, defense, fortification) |
| refuge(noun, place, keep, protection, defense) |
| tower(noun, hold, part, keep, top) |
| cage(noun, prison) |
| redoubt(noun, support, cover, position, top) |