USS Constellation is a sloop-of-war, the last sail-only warship designed and built by the United States Navy. She was built at the Gosport Shipyard between 1853 and 1855 and was named for the earlier frigate of the same name that had been broken up in 1853. The sloop's primary armament was 8-inch (203 mm) shell-firing guns and four 32-pounder long guns, though she carried other guns as well, including two Parrott rifle chase guns. Constellation's career as a front-line unit was relatively short; after entering service in 1855, she served with the Mediterranean Squadron until 1858, and in 1859, she was assigned as the flagship of the Africa Squadron, where she served with the African Slave Trade Patrol. During the American Civil War (1861–1865), the ship returned to the Mediterranean to patrol for Confederate vessels. In late 1864, she returned to the United States to be decommissioned, as most of her crews' enlistments had expired. She spent the rest of the war out of service.

Constellation was recommissioned in 1871 for use as a training ship, being used for shooting practice and training cruises for midshipmen. She filled this role for twenty-two years, and during this period, she saw a number of other activities, including transporting exhibits for the 1878 Exposition Universelle in Paris and carrying food to Ireland during the 1879 Irish famine. She was reduced to a stationary training hulk in late 1893, being moored in Newport for the next twenty years. During this period, the mistaken belief that the two Constellations were one and the same arose, and she was presented as such in 1914 during the centennial of the writing of "The Star-Spangled Banner", the national anthem of the United States. Briefly renamed Old Constellation in 1917 to free the name for a new battlecruiser of the Lexington class, she reverted to her original name when the battlecruiser was scrapped in 1925. Constellation was recommissioned in 1940 as part of the build-up in anticipation of the United States' entry into World War II, during which she served as the port flagship of the commander of the Atlantic Fleet.

Proposals to restore the vessel as a museum ship had been submitted already in the 1930s, but work began in earnest after World War II. Shortages of funds prevented her transfer to the city of Baltimore, Maryland until 1955. Operating under the mistaken belief that she was the original Constellation, the organization responsible for the ship modified her to match the earlier vessel's appearance during a refit in the late 1950s and early 1960s. During this period, a controversy arose over the vessel's identity that lasted into the 1990s, when new research definitively proved that the Constellation launched in 1797 and the 1854-launched vessel were distinct ships. Periodic repairs have been carried out since the mid-1990s to repair rotted wood. Constellation remains open to the public as part of the Historic Ships in Baltimore in the city's Inner Harbor, having been designated a National Historic Landmark.