mighty fortress
- strongholdFortified place of defense
- castleFortified medieval residence
- citadelFortified urban stronghold
- bulwarkDefensive fortification or safeguard
- bastionFortified defensive position
ramparts · tower · impregnable · walls · battlements · refuge · sanctuary · hymn · Luther · unshakable · invincible · protection · defiant · stone · moat · keep · iron · steadfast
structural strength and defensibility
mighty fortresscardboard box
Rigid paper container
open field · paper house · house of cards · tent · sand castle