Ono-jo Castle (an ancient mountaintop castle in Chikuzen Province) (大野城 (筑前国))
Ono-jo (also known as Ononoki) Castle was an ancient mountaintop castle (Korean-style mountain castle) constructed in the Asuka period, which was located on Mt. Shioji in Chikuzen Province. It is located at Umi Town and Onojo City, Fukuoka Prefecture. It was designated as a special historic site on March 31, 1952.
The construction site of the Ono-jo Castle is analogically considered the Shioji mountain range with the highest peak of approximately 410 meters above the sea at the north of Dazaifu. On Mt. Shioji, over 5200-meter long earthwork are casted up from the ridge through the hillside to the valley where the stone walls are built. The castle has some gates; one in the north, one in the southwest, and two in the south, and at the six of higher and flat places in the castle, at 36 places in total, the foundation stones are remained. These are the remains of warehouses, in which not only weapons of war but grains and so on were stored judging from the fact that carbonized grains of rice and so on were detected.
It is considered to have been a castle for the defense of Tazaifu in view of the location to the north of Dazaifu.
The ridge extending westward is called Hinoozaki, where a fire beacon platform site, Koho, the site which is deemed to have been what is now called army post and the ruins of Bishamonten (Vaisravana) are located. In the vicinity, ancient artifacts like kyozutsu (sutra case, container) and so on were also excavated.
In addition, the name of Onojo City derives from this Ono-jo Castle.
This mountain is also called Mt. Shioji, which derives from the fact that Shio-in Temple on Mt. Enman was built on the mountaintop in 774 praying for repulsing the foreign enemy. Carbonized grains of fried rice were also discovered in the area around foundation stones which are considered to be the remains of the store of the temple.
In the Battle of Hakusukinoe in 663, Wakoku (later known as Japan) aiming at a revival of Paekche was defeated by Silla-Tang allied forces. "Nihonshoki" (Chronicles of Japan) describes that Wakoku had constructed various defense facilities to strengthen the defenses.
In 664, Sakimori (soldiers garrisoned at strategic posts in Kyushu in ancient times) were garrisoned and fire beacon platforms were set up in Tsushima, Iki, and Tsukushi Provinces, and Mizuki (Water Fortress) was built to the west of Dazaifu.
In September 665, a castle was built in Nagato Province.
In the same month in the same year, Fukuru OKURAI and Fukufu SHIHI, exiled from the Paekche were dispatched to Tsukushi Province and made to build a castle in Ono and Ki respectively.
Out of these, the castle built in Ono in Tsukushi Province was the Ono-jo Castle. The castle built in Ki was identified as Kii-jo Castle.
On April 6, 2006, the Ono-jo Castle was selected as one of the Japan's 100 Finest Castles (the 86th) and from June 2007, the Japan's 100 Finest Castles stamp rally started.