Kato Yoshiaki began the construction of a castle at the summit of 132m high Mt. Katsuyama in 1602. The Honmaru at the peak was surrounded by tall stone walls 10m or more in height. It was a complex design, with yagura watchtowers built at various key points and connected by earthen walls. When Matsudaira Sadayuki became the lord of the castle in 1635, he demolished the five-story tenshu built during the Kato period and reduced it to a three-story keep with basement. This tenshu and the Honmaru’s main structures were destroyed by fire from lightning strike in 1784. The tenshu complex was finally rebuilt in 1852, towards the end of the Tokugawa period. Presently, 21 buildings, including the tower complex survive on the mountaintop and are designated Important Cultural Properties. There are 30 additional reconstructed wooden buildings, returning the Honmaru to its original appearance, except for the earthen walls. The huge well in the reconstructed ruins of the Ni-no-maru Goten Palace is also a recommended viewing point.