Aizuwakamatsu, the main city in the Aizu district of Fukushima, was a castle town during the Edo Period. Inside the city are many historical buildings and sites, such as Tsuruga Castle, Oyaku-en Garden, that belonged to the lord of Aizu, samurai houses, Mt. Iimori-yama (a symbol of the process in the formation of modern Japan), and Otsuka-yama-kofun, one of the oldest burial mounds in the Tohoku region.