Tsugaru-Fukushima Castle was the biggest castle in the Tohoku region until modern times. It had a 650,000-square-meter outer ward and a 40,000-square-meter inner ward.

Within the site there is evidence of pit dwellings, outer and inner moats, mounds as well as gate and wall pillars that date to ancient or medieval times.

The castle was the base of the Ando family, which controlled the port of Jusan. Excavation in 1992 revealed that the castle was a full-dress castle with solid mounds and large moats. Moreover, despite an accepted theory, no medieval relic was found predating the 11th century. So, it is likely that Fukushima Castle was built in the 11th century and the inner ward was where soldiers were assembled and some rituals were held.

In the 8th year of the Keicho period (1603), the daimyo Tsugaru Tamenobu, who helped unify the Tsugaru domain, first made plans for this castle. But it was not until two generations later, in the 15th year of the Keicho period (1610), that Nobuhira commenced construction to complete the castle two years later. The castle became the Tsugaru family house and remained the center of Tsugaru domain politics for 260 years until the abolition of the domain.

The castle consists of six parts: main, second, third, fourth, north and west in grounds of about 49.2 ha. It is very rare that so much of a 400-year-old castle has been preserved, including a tower, gate, and triple water moats.

There is a small three-storied castle keep located near the southwest wall. The tower harmonizes tastefully with the four seasons that include cherry blossom in spring, the moon in summer, the moon, the maple in autumn and snow in winter.