fortification
/ˌfɔ:tɪfɪˈkeɪʃn; ˌfɔrtəfə`keʃən/ n
1 [U] fortifying; strengthening 加强防卫; 强化
plans for the fortification of the city 加强城市防御的计画.
2 [C usu pl 通常作复数]
tower, wall, ditch, etc built to defend a place against attack 碉堡、 围墙、 战壕等防御进攻的建筑物
These fortifications were all built during the last war. 这些防御工事都是上次战争时修筑的.