13. 109th Iman Fortified
This partial-underground bunker is located in Japan and used to house troops and work as a defense bunker during World War II. Most of the action that took place around this area was between the Japanese and the Soviets, though the Soviets found the bunker difficult to destroy. After the war, the site was abandoned and Mother Nature reclaimed the area, but some beautiful graffiti has since been tagged on the compound by street artists from around the country. Quite amazing, right?