What is the name of the Island located in San Francisco Bay, 1.25 miles offshore, with facilities for a lighthouse, a military prison, and the Parade Grounds, a large concrete open area?
Alcatraz Island Alcatraz Island ( ) is located in San Francisco Bay, 1.25 mi offshore from San Francisco, California, United States. The small island was developed with facilities for a lighthouse, a military fortification, a military prison (1868), and a federal prison from 1934 until 1963. Beginning in November 1969, the island was occupied for more than 19 months by a group of Native Americans from San Francisco, who were part of a wave of Native activism across the nation, with public protests through the 1970s. In 1972, Alcatraz became part of a national recreation area and received designation as a National Historic Landmark in 1986.
Japanese 20mm Cannon Blockhouse The Japanese 20mm Cannon Blockhouse is one of many relics of World War II on the island of Saipan in the Northern Mariana Islands. It is a concrete blockhouse, semi-circular in shape with a diameter of about 6 m . Its walls are 1.22 m thick with four firing ports large enough to accommodate 20mm cannons, originally equipped with steel sliding shutters. A steel door 25 mm thick provides access to the structure at the rear, sheltered by a concrete wall and covered defensively by a machine gun port. The blockhouse is located near the center of what is locally called Big Agingan Beach (Unai Dankulo Agingan), on the south coast of the island, about 20 m from the shore. It was built in some haste by the Japanese forces defending Saipan in 1944, and was captured by Allied forces early in the Battle of Saipan.