The ship consisted of a heavy, round iron turret on the deck, which housed two large cannon. The armored deck was barely above the water line. Aside from a smoke stack and a few fittings, the bulk of the ship was below the water line to prevent damage from cannon fire (torpedoes were not a worry for another 50 years). Monitor was launched on 30 January 1862.
Monitor was one of the most innovative naval vessels of all time. It was the first ship made almost entirely out of iron. Parts were forged in nine foundries and brought together to build the ship. The entire process took less than 120 days. Other innovations included the "cheesebox", which was the first rotating turret, it was the first naval vessel fitted with Ericsson's marine screw and it even anticipated some aspects of submarine design by placing all facilities but the turret under water. In contrast, Virginia, erroneously known by its Yankee name Merrimac, was a conventional wooden vessel covered with iron plates and with fixed weapons.
In 1974, the wreck of Monitor was located on the floor of the Atlantic Ocean off Cape Hatteras, North Carolina. The wreck site was designated as the United States' first marine sanctuary. The Monitor Sanctuary is the only one of the thirteen national marine sanctuaries created to protect a cultural (as opposed to a natural) resource.