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.

Walls are built around castles and towers as protection. These walls are usually made of stone, and are mounted within the basic structure of the architecture.

Walled fortresses can be seen in many world civilizations. Although, the styles differ, the basics are the same; some are beautifully made and some have special features, such as ducts for discharging water.

In Japan, walling can be seen especially in castles and castle towns. The Ano Group from Kunie are famous for their designs of fortresses and their beautifully designed walls. Also, in the Ryukyu Islands, it was common practice to put stones on roofs and the surroundings to protect their houses from fierce winds and storms.

Hachiman-bori is a canal that was used to transport goods for the flourishing trade of the wealthy Omi merchants (Omi shonin).

During the late Edo period, the canal was as crowded as that in nearby Otsu, yet after World War II, it fell into disuse, due to the development of onshore communication.

Hachiman-bori is 15m wide and 6km long. It was established when Hachiman-jo castle was built, first as a moat for protection from enemies and second, as part of the urban planning of the castle town.

Alongside the canal are white walls and old houses that show the ostentatious wealth of the city back then. Nowadays the canal has been re-constructed as a leisure venue with renovated piers etc.

Sendai Castle is located on Mt Aoba in Sendai, Miyagi Prefecture. Constructed in 1601, the castle is also known as Aoba Castle. Date Masamune established the castle during the Keicho years. For 270 years it was the home of the Date family and the Sendai clan's seat of government. Due to its inconvenient setting on a mountain, the Date family moved from Sendai Castle to Wakabayashi-yakata.

Sendai Castle is constructed in a circular enclosure system with Hon-no-maru in the center and Ni-no-maru, Higashi-no-maru and San-no-maru on the outer sides. The buildings are protected by Hirose River, and to the south by Ryu-no-guchi Valley.

After crossing Hirose bridge and climbing the gentle hill, one sees the ruins of the Ote Gate, which was said to resemble a reconstruction of Hizen Nagoya Castle. Ote Gate was destroyed by war, but today the restored gate and fortress give a a feel of the old atmosphere of the castle in former times.

Sanuma Castle was established some time between 1185 and 1187 by Terui Takanao, a close aide of Fujiwara no Hidehara. After the collapse of the Fujiwara clan, Sanuma Castle came under the control of Kasai, a subordinate warrior of Minamoto no Yorimoto. However, in later years, the castle was a residence of Ishikawa, a retainer of the Osaki clan.

Sanuma Castle is also known as Shishiga Castle, because deer were buried here in the past as a form of protection. The castle is a natural fortress protected by swamp and river. Today, the Hon-maru (main building) has become the Shishiga Castle park. In the past, to the southwest of Ni-no-maru, there used to be a swamp called Tai Numa, which made a natural moat to protect the castle. Along the eastern side of the Hon-maru ruins, flows the Hazawa River, which also formed a natural moat.

Also in the vicinity stands Izumo Shrine's Teruhi Kengen. Near this shrine is the Sanuma Memorial Tablet, which is a record of the castle. Earthworks can be seen at the edge of the castle, giving a hint of the former castle.

Nakatsu Castle is a 'water castle' located in Nakatsu, Oita Prefecture. Construction of the castle was undertaken by the master of fortifications, Yoshitaka Kuroda, who was gifted six Toyomae counties by Hideyoshi Toyotomi.

The foundations for the castle were arranged in a fan shape on a piece of land near the mouth of the Yamakuni River, and it was also known as 'fan castle'. Due to the fact that the Yamakuni River flows into the Toyomae sea, the castle moat is filled with seawater. This makes Nakatsu Castle a water castle, and it is counted as one of the three best water castles in Japan.

Inside the castle are many interesting displays of costumes, swords, armory, as well as old pictures and writings. Nakatsu Castle is now part of Nakatsu Park. It is also part of the premises of Nakatsu Shrine. A mock main keep and corner tower were built in 1964 and are currently used as a museum.

Nakatsu Castle is an ancient fortress built during the Warring States period, and is also the symbol of Nakatsu.

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.

Tsugaru Tamenobu used Horikoshi Castle for integrating the Tsuruga domain and as a base for the Hirosaki clan. It became the main clan castle when Tsugaru Tamenobu moved there from Ora Castle in the third year of the Bunroku period (1594), until the 16th year of the Keicho period (1611), when the 2nd clan head, Tsugaru Nobuhira, moved to Hirosaki Castle.

In November 1985, the castle was designated as a national historical site. Since 1998, in order to develop it as an historical park, excavation was carried out that revealed pillars, celadon and white porcelain as well as lacquerware.

Today, Horikoshi Castle is part of the grounds of the Kumano Shrine. National Highway 7 runs through part of the area. In the shrine, the mounds and dry moats recall the atmosphere of the old castle.