Remember a while back when I mentioned that the USS Iowa's citadel was 17 inches thick, and so were it's doors? As you can see, I wasn't pulling your leg. It's thicker than the museum staffer over there. XD

This is the DOOR to the bridge citadel, and it's not only the thickest armor on the ship, but it was also forged as a single piece of metal --- no welding, bolting, bracketing, or lamination, and that thick Copper band is there only to serve as a cushion!

It's also made of one of the highest-quality Steels ever used on a warship as well; RHA Nickel Steel. This alloy is what makes US Battleships of the 1930s and 40s a cut above all others those two decades, because only the United States built it's Battleships ENTIRELY from Nickel Steel. That's also the reason why the Iowa is in such an excellent condition, despite many decades of neglect that have turned lesser ships into floating rustbuckets.

Finally, this big f***er weighs over 4 tons!