At the top of Mt. Hiji-yama, viewing the Ueno Basin to the east, are the ruins of Hijiyama-jo Castle, the scene where the fierce battle between the Iga clan and Oda forces took place during the Tensho Iga War.
The ruins are large, stretching approximately 200 meters east to west and 400 meters north to south.
Kannon-ji Temple originally existed on the site of Hijiyama-jo Castle; however, the temple was converted into a castle at the end of the Warring States period in preparation for the invasion by Oda Nobunaga.
Ruins of the heavily defended Hijiyama-jo Castle tell the story of the fierce battles during the Tensho Iga War.