Gunpowder/explosives magazine, Certified and inspected, ID measurements; 7 1/2ft long x 5 1/2 wide x 7ft high, 7/16 plate steel walls and roof, 1/2 door with covered lock, 3/4 plywood interior with gap in walls for sand, used a tow truck with a tilt deck to move, bloody heavy! Cost $8,000 to build 40 yrs ago.