The U.S. Navy has, over the years, donated a large number of ships for use as memorials or museums. Most of these contributions have taken place since World War II. This "memorial fleet" consists of eleven submarines (all non-nuclear, including the Drum, Silversides, Cavalla, Cobia, Batfish, Pampanito, Albacore, Becuna, Clamagore, Blueback, and Growler), five aircraft carriers (Lexington, Midway, Yorktown, Intrepid, and Hornet), seven battleships (Texas, Arizona, North Carolina, Massachusetts, Alabama, New Jersey, and Missouri), six destroyers (The Sullivans, Kidd, Laffey, Joseph P. Kennedy Jr., Turner Joy, and Stewart), two cruisers (Salem, Little Rock), one fast patrol craft (PTF-17), two 19th century wooden warships (Constellation and Constitution) and one steel 19th century warship (the cruiser Olympia). All of these ships are decommissioned, except the Constitution, which is still technically part of the navy ("in commission.) One of the ships is just a memorial, the battleship Arizona at Pearl Harbor. There are a number of smaller warships (like PT boats) and noncombat ships (tugs and amphibious boats) that were given away for use as memorials as well. These ships have proved popular attractions, as have similar ships in other nations.