 Several memorials were established in Pearl Harbor to remember the Japanese airstrike on U.S. naval forces on December 7th, 1941. These memorials now draw in several million people from the U.S. and other nations each year. The most well-known of these attractions is the USS Arizona Memorial. Visited by more than one million people annually, the memorial is accessible only by boat. The memorial itself crosses above the middle of the sunken hull of the ship without touching it. Oil from the Arizona still rises from the wreckage. The oil is referred to as the Tears of the Arizona. Arizona was declared a national historic landmark May 1989. Another memorial is the still submerged wreck of USS Utah. The campsites wreck was only partially rided to clear an adjacent berth in 1944. It was dedicated as a memorial in 1972 and declared a national historic landmark in 1989. Although the ship is no longer at Pearl Harbor, the legacy of USS Oklahoma lives on in a memorial dedicated in December 2007. The black granite wall suggests the hull of the Oklahoma, while the aligned marble represents the crew manning the rails. USS Missouri was the last U.S. battleship launched and the last to be decommissioned. The mighty Moe served as the platform where Japan signed its unconditional surrender to Allied forces on September 2, 1945, ending the Second World War. After its final decommissioning in 1992, Missouri was eventually transferred to Fort Island in Pearl Harbor. It opened as a museum January 29, 1998.