October 21, 1797 "Old Ironside" was launched. It was nicknamed this during the War of 1812. A British ship's shots at her, seemed to bounce off the hull. Her hull was made of live oak supposedly the strongest wood in North America. The bottom is covered with copper provided by none other than Paul Revere.
She is the oldest commissioned ship in the US. She is guarded by naval personnel. You must pass through security and show ID. to visit the ship.
It feels like you have gone back in time. It is a free tour by naval officers or casually tour on your own. Well worth the walk across the bridge over Boston Harbour.