The Matsushiro Zozan Underground Vault in Matsushiro-machi, Nagano City, is a huge underground bunker that was excavated as part of a covert plan to move government ministries, the army, and the Imperial headquarters from Tokyo to Matsushiro in order to prepare for decisive mainland battles during the end of the Second World War. Dug out like the intersections on a Go board game with Mt. Maizuruyama at the center and extending out to Mt. Minakamiyama and Mt. Zozan, about 80% of the project was completed, but the war came to an end and construction was stopped. In 1989, it was outfitted with tourist facilities, and currently one part of the approximately 10-kilometer-long cavern is open to the public as a historic wartime relic.

Photograph provided by Nagano Convention & Visitors Bureau