There are various synonyms to refer to a Japanese castle, which has been a symbol of Japan's architectural and cultural heritage. These castles, also known as Shiro, were built during the feudal period as part of a defense system and were owned by the feudal lords, known as daimyos. Some of the synonyms to refer to a Japanese castle include Hashiro, which translates to fortified tower, Tenshu, which refers to the main tower or keep of a castle, and Yagura, referring to a multi-story tower built for defense purposes. Other synonyms are Kuruwa, which denotes the castle complex, and Sannomaru, referring to the third defense area of the castle. Japanese castles vary in size, design, and purpose, and they are an integral part of Japan's rich history and culture.