Karatsu, Saga
Due to its proximity to mainland Asia, Karatsu has long been known as a stopover to Korea and China.Under ritsuryō, the current city area was part of the Hizen Province. In 1591, on the coast of the northern part of the city (formerly the town of Chinzei), Nagoya Castle was constructed. The following year, it became the location from which the Imjin War was launched by Toyotomi Hideyoshi. In the middle of 1593, Terasawa Hirotaka created the Karatsu domain and began governing it. In 1602, replacing Nagoya Castle, Karatsu Castle was constructed in what is now the heart of Karatsu. The tower of Karatsu Castle was built in 1966 .
Japanese castle
Originally conceived as fortresses for military defense, Japanese castles were placed in strategic locations, along trade routes, roads, and rivers. Though castles continued to be built with these considerations, for centuries, fortresses were also built as centres of governance. By the Sengoku period, they had come to serve as the homes of "daimyōs" (feudal lords), to impress and to intimidate rivals not only with their defences but also with their sizes, architecture, and elegant interiors. In 1576, Oda Nobunaga was among the first to build one of these palace-like castles: Azuchi Castle was Japan's first castle to have a tower keep (天守閣, "tenshukaku"), and it inspired both Toyotomi Hideyoshi's Osaka Castle and Tokugawa Ieyasu's Edo Castle. Azuchi served as the governing center of Oda's territories, and as his lavish home, but it was also very keenly and strategically placed. A short distance away from the capital of Kyoto, which had long been a target of violence, Azuchi's carefully chosen location allowed it a great degree of control over the transportation and communication routes of Oda's enemies.