In 1575, Nagachika Kanamori built the castle (citadel, Ninomaru, Sannomaru) at the top of Kameyama mountain. It was built as a defense facility. A castle town, which was one of the forms of the city in Japan, was established around the lord's residence. The castle tower built by Nagachika Kanamori is a Hirayama-jiro, which is a castle built on a hill in the plains.