The former Japanese army's arsenal was in this area.
Engineers working at the armory maintained the weapons.
工廠 refers to a military arsenal or factory, especially for naval ordnance; 兵器廠 is broader and can include storage and administration.
Compound of 兵器 (weapons) and 廠 (factory, workshop, or depot). The character 廠 is used in military and industrial contexts for a facility or plant.