The USS Constitution is the oldest commissioned warship still afloat. Constructed in Boston in 1797, she was one of the United States Navy's first men of war. Her exploits during the War of 1812 made her the stuff of legend. During the great naval battle where the Constitution captured the British ship Guerriere, a sailor on the Guerriere saw 18-pound British cannonballs bouncing right off the oak hull of the Constitution. He exclaimed, "Huzza, her sides are made of iron!", giving the ship its legendary nickname.

Source: USS Constitution Museum