Eng

Fortress...

堡

Bastion, Fort, Fortification, Fortress, Hamburger, Military, Stronghold, Walled

塞

Block, Cork, Fortress, Frontier, Perform, Seal

堡壘

Fortress

要塞

Citadel, Fortress, Stronghold

城堡

Castle, Castles, Fortifications, Fortified, Fortress