Chiayi County Castle was the county seat of Taiwan's Chiayi County (Zhuluo County) during the Qing Dynasty, located in today's Chiayi City, and was the earliest city to be built in Taiwan. According to its building materials, it can be successively categorized into four periods, namely, the bamboo city, the soil and bamboo city, the triple-hexed soil city, and the brick and stone city.