Introduction to Inuyama Castle: Inuyama Castle is located on a cliff about 40 meters above sea level south of the Kiso River in Inuyama City, Aichi Prefecture, Japan. It is also known as Baidi Castle and is a Japanese national treasure building. It is a flat mountain castle between hills and plains, and has the oldest existing castle in Japan. Visitors can experience the life style of the Japanese samurai class in the Middle Ages.