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 .
Inuyama Castle
Inuyama Castle is often claimed as the oldest castle in Japan. Its original construction was completed in 1440. According to "Engishiki" (a Heian Period-book), Haritsuna Shrine (a Shinto shrine) was moved to make way for the castle. That structure has been heavily augmented over time, and the current towers were completed in 1537, by Oda Nobuyasu, Oda Nobunaga's uncle. Though the antiquated architectural style of the watchtower atop the "tenshu" has in the past led many historians to believe this to be the oldest extant "tenshu" in Japan, that honor goes to Maruoka Castle, built in 1576. Construction on the main "tenshu" ("donjon") at Inuyama began in 1601, and continued through 1620.