這個空間是以前的五七戰防砲堡。在海防據點中，砲堡是一座大型的地下碉堡，就像機槍堡，砲堡的頂層會有水滴狀的消音椎。五七戰防砲堡是一個梯形空間，射口的上方畫有目標寫景圖，左右兩側牆面上則畫有戰備所需資訊。

57 Cannon Fort This space used to have a 57 mm artillery cannon. It is a large underground bunker, and similar to the machine gun bunker, it also has the noise reduction cones on the ceiling. The 57 Cannon Fort is a staircase shaped space, with a target landscape chart above the nozzle opening, and equipment operation information on the walls on both sides.