The ruins of Takeda Castle are located in Asago City, Hyogo Prefecture. The construction of Takeda Castle is still unknown, and it is said that a mountain castle already existed there before the Warring States Period in Japan. The known remains of Takeda Castle are located on top of Kojo-zan (Mt. Kojo), 353.7 m above sea level, and measures 400 m from north to south and approximately 100 m from east to west. Although it has been 400 years since the castle was abandoned, the stonewalls remain almost intact, making it one of the largest existing mountain castles in Japan. Morning fog sometimes forms in the early morning of a clear late autumn morning, and the sight of the castle surrounded by a sea of clouds is reminiscent of a castle floating in the sky. For this reason, Takeda Castle Ruins is also called "Castle in the Sky" or "Machu Picchu of Japan. Many tourists visit the area to catch a glimpse of this fantastic sight.