Hiroshima Castle (広島城, Hiroshima-jō), sometimes called Carp Castle 
(鯉城, Rijō), is located in Hiroshima in Western Japan. This castle served for more than two centuries as a residence of the daimyo (feudal lord) of the Hiroshima or Geishu han (domain).
Japanese castles (城, shiro or jō) are one of the symbols of the Edo period and samurai era in Japan. The largest of them is Edo castle which was the residence of the Shoguns in Japan in Edo period. Since the Meiji Restoration it has been used as the residence of Japanese Emperors.
Japanese Castles evolved with the development of warrior’s society and it’s structure. The Edo period was the peak and golden age of Japanese Castles.
Castles were the administrative centers of domains and residences of the rulers who were called “tonosama” and daimyo. The castles are fortresses built primarily of wood and stone, and have moats, walls and towers.
Castles of the Edo period were considerably larger than the wooden fortresses of earlier centuries and mountain castles (built on the top of the mountains) used mainly for defense. Also, they had different types and varied in size, for example, mountain Castles, castles on a hill in the plains, and castles on the plains. Hiroshima Castle is considered as kind of castles on the plains near the sea coast.
Today there are more than one hundred castles in Japan restored fully or partially, but their number in the past possibly exceeded several thousand.  Only several castles, such as the ones at Matsue and Kochi, remain in their original form. The Geishu region was well-known for mountain castles that reached several dozens in number, but most of them were dismantled at the beginning of Edo period.

Most castles became objects of reconstruction after World War II.  Hiroshima Castle belongs to this type, because it was completely destroyed in the atomic bombing since the distance to epicenter did not exceed 780 meters. The Castle tower was partly rebuilt and made of concrete. Now, the 39 meter high Central tower serves not only as a symbol of Hiroshima Castle, but also as local history museum. The Central Tower is all used as an exhibition place with permanent and temporary exhibits.

Now tourists can see the Central Tower – Tenshukaku (rebuilt in 1958), the main gate Omote gomon, and a part Ninomaru (the second compound) restored in 1994, just before the Asian games were held in Hiroshima.

The budget of this Ninomaru’s project is estimated up to 1.5 billion yen, or about 15 million dollars, made possible to restore the part of wall and two small towers called “yagura”.

One of the yagura is called the taiko yagura or Drum Tower because it held a huge drum used to announce the opening or closing of the main gate or to call samurai to gather for the castle meetings.
Also, there was the horse stable here for several horses used by the lord.

Eucalyptus was planted in 1935.

The back gate called, Ura gomon, was located where the RCC television station now stands and has not been restored. In front of the Ura gomon across the moat, you can see the torii or a traditional gate commonly found at the entrance of the Shinto shrine. This torii is the original one that stood in front of the original Gokoku Jinja shrine at the time of atomic bombing. Later the Gokoku Jinja was rebuilt in a new location within the modern castle with a new gate, and the old torii gate was placed before the Ura gomon.

Japanese castles had many differences with European castles. Unlike in Europe, where the mass production and use of the cannons put an end of the age of castles, Japanese castles of the Edo period were the result of the import and use of firearms. The openings are different in shape to be used for shooting with bows and arquebuses.
The first firearms appeared in Japan in 1543, and led to an increase in the size of castles and their design. The use of arquebuses and cannons in Japan changed many aspects of life including warfare. The castles raised to large fortresses that should protect the samurai lord, samurai and their families living inside of the territory surrounded by several walls and moats. So the central part of the castle was built quite far from the outer moat and wall to prevent the in-coming shells and bullets from outside.
In contrast with earlier castles called yamajiro (mountain castles) like Yoshida-Kooriyama Castle of Mori family, castles of new type as in Hiroshima were located on the delta of the river called Otagawa where there are no densely forested mountains or hills, relying more heavily on architecture and manmade defense facilities (walls and moats) than on its natural environment for protection. Nevertheless, the Otagawa river was integrated in the defense facilities and served as a part of the outer moat.
Azuchi castle, built in the 1570s, was the first example of a new type of castle, giving a model to many others including the Hiroshima castle with a large stone base (Ishigaki), long passageways, inner compounds (丸, maru), and a high central tower (天守閣, tenshukaku) and small towers (Sho tenshu小天守). The Imabari Castle was the first castle on the plain near the sea coast that was designed by Todo Takatora and had a five stored Tenshukaku.

Hiroshima castle was originally constructed in the 1590s by Mori Terumoto, one of Toyotomi Hideyoshi's council of Five Elders. Mori Terumoto had huge land holdings up to 1 mln. 200 thousand koku (one koku – about 150 kg of rice).Terumoto served as a chief commander of the western forces in the key Sekigahara battle in 1600 where western forces experienced a great defeat. After this defeat, Terumoto’s holdings were cut to one third and his headquarters transferred from Hiroshima to Hagi, called from that time the Choshu domain.
Later it was substantially reconstructed under the direction of the second lord of Geishu han – Fukushima Masanori who was also one of the prominent lords of Hideyoshi’s time. Fukushima largely extended the size of the castle and used for decoration a lot of gold as his lord Toyotomi Hideyoshi liked.

In the time when the construction of the castle began, there was no Hiroshima city or even this geographical name. The area was called Gokamura, meaning "five villages" located on the sea coast near the old famous temple “Fudoin” belonging to the Shingon Buddhist school. In 1591, Mori Terumoto moved from Yoshida-Kooriyama Castle located in the mountains and was not appropriate for the governing of nine provinces in possession of his family. Mori represented one of the most powerful families of Sengoku period and controlled much of what is now Shimane, Yamaguchi, Tottori, Okayama and Hiroshima Prefectures at Honshu and a part of Fukuoka prefecture around Kokura city at Kyushu.
After the Sekigahara battle, the Mori family left Hiroshima, which became the main stronghold of Fukushima Masanori, who extensively enlarged the castle and made the central part similar to the “Jurakutei” in Kyoto. But in 1619 Masanori was punished and moved to the smaller Kawanakajima domain with the kokudaka of only 45 thousand koku. Masanori was accused of violation of “Buke shohatto”(the code for samurai houses) rules when he provided unproper information about repair works in one of the towers (yagura) damaged by flood.

Hiroshima was transferred into the hands of the Asano family. The Hiroshima Domain was ruled for most of the Edo period by the daimyo of the Asano clan and encompassed Aki Province and parts of Bingo Province with an estimated rice value kokudaka of 426,500 koku.