Guide
The Matsushiro Zozan Underground Ruins are a large-scale underground structure located in Matsushiro Town, Nagano City. The site utilizes the geologically firm bedrock surrounding Mount Maizuru, Mount Kaishin, and Mount Zozan. The facility features a massive network of spaces carved into the earth, with a total length of approximately 10km. About 80% of the construction was completed before it was abandoned, leaving a striking physical record of the intense atmosphere of that era. The structure remains a significant historical monument today.
These underground tunnels were part of a plan to relocate the Imperial Government and various ministries to this location to serve as a base for a final defense of the Japanese mainland during the final stages of World War II. The construction was a rapid, high-pressure project that lasted only about nine months, starting from November 11, 1944, until the end of the war the following year. It is said that a massive amount of money—estimated at 100 to 200 million yen at the time—was invested in this project, involving a vast mobilization of people. Since 1989, portions of the site have been opened to the public as a war-time heritage site to pass this history down to future generations.
The greatest draw is the opportunity to actually enter and walk through the underground tunnels. You can witness the vast spaces carved directly into the bedrock and see the traces of the construction techniques used at the time. The atmosphere inside the tunnels is unique compared to the surface, providing a visceral sense of being within a historical monument. By wearing a safety helmet and walking through the passages, visitors can truly grasp the immense scale and structural complexity of the site.
While the temperature inside the tunnels tends to remain relatively constant throughout the year, there is often a temperature difference between the underground and the surface. It is recommended to dress according to the current season. The facility is generally open from 9:00 to 16:00 (last entry at 15:30). Please note that while the site is open on the 3rd Tuesday if it falls on a public holiday, it is typically closed on that day. It is best to check the schedule in advance.
Visitors can experience a physical tour of the underground passages. Wearing a helmet, you can directly observe the texture of the excavated bedrock and the sheer expanse of the underground space. This is more than just a static museum exhibit; it is an immersive, physical experience of being inside a massive structure. Additionally, the surrounding Matsushiro area offers cultural experiences, such as traditional Matsushiro-yaki pottery making.
The Matsushiro area is dotted with historical landmarks, including traditional samurai residences, workshops for the traditional Matsushiro-yaki pottery, and historical buildings like the Yamadera Josan Estate. You can easily combine a visit to the underground ruins with a tour of the historic streets and traditional culture of Matsushiro.
As you will be walking through the underground tunnels, please wear comfortable walking shoes, as the terrain can be uneven with steps and uneven surfaces. Helmets are provided on-site. Eating, drinking, smoking, graffiti, or holding gatherings inside the tunnels is strictly prohibited. While admission to the ruins is free, please prepare cash or a card if you plan to use nearby facilities or shops. English support availability may vary depending on the situation at the site.