Over a million people visit the capital city of Nagano in Nagano Prefecture annually. The city was built around Zenkoji Temple, one of Japan’s most popular temples and in 1998, hosted the Winter Olympic Games. Located just half a mile south of Nagano City, you will find the pleasant former castle town of Matsushiro. The city is recognized for its samurai houses, gardens, museums and for a tourist attraction known as the Matsushiro Underground Imperial Headquarters.
The Matsushiro Underground Imperial Headquarters is a massive underground bunker complex built during WWII. As the course of the war deteriorated, an absolute national defense zone was set by the military in September 1943 identifying an area that they had to secure at any cost. However, when Saipan, the most important strategic point in the South Sea within the zone fell on July 1944, the decision was made to transfer the Imperial Palace, the army headquarters and other important governmental departments to Matsushiro.
Construction of the bunker began on November 11, 1944 and continued until Japan’s surrender on August 15, 1945. At the time, construction was 75% completed with 63,040 sq. ft. of floor space excavated. In total, 7,000 Koreans and 3,000 Japanese laborers worked three eight-hour shifts and later two twelve-hour shifts to build the complex at a cost of ¥200,000,000. The complex, designed specifically to withstand B-29 bombings, was an interlinked series of tunnels underneath several mountains. The plan was to have the facilities for the Imperial General Headquarters and Palace constructed under Mount Maizuru, the military communications under Mount Saijo, government agencies, NHK and central telephone facilities under Mount Zozan,; the residences of the Imperial Family under Mount Minakami and the Imperial Sanctuary under Mount Kobo.
Although the bunker was never used as originally intended, it was utilized by other agencies after the war. In 1947, the Meteorological Agency set up a seismographic office in the concrete building that was constructed at Mount Maizuru. An assortment of seismographs and equipment were installed making it the largest office of its kind in Japan. In 1967, the Matsushiro Earthquake Center was set up following a local earthquake. In 1990, parts of the Mount Zozan bunker were opened by the Nagano Municipality and Shinshu University set up an astronomical observatory inside.
Today, the complex is administered by Nagano City’s Sightseeing Bureau. Visitors are permitted to explore the first 500 meters of tunnels under Mount Zozan, the rest of the facility is off limits to the public. Comprised mostly of those interested in war time history and school children learning about the local history, the complex hosts over 100,000 visitors annually.
Web page: http://www.matsushiro.org/daihonei/