Kumamoto was a large and well-fortified castle. The castle keep is a concrete reconstruction built in 1960, but several ancillary wooden buildings remain of the original castle. Kumamoto Castle is considered one of the three premier castles in Japan, along with Himeji Castle and Matsumoto Castle. Thirteen structures in the castle complex are designated Important Cultural Property.
Kumamoto Castle's history dates to 1467 when fortifications were established by Ideta Hidenobu. In 1496, these fortifications were expanded by Kanokogi Chikakazu.
In 1588, Katō Kiyomasa was transferred to the early incarnation of Kumamoto Castle. From 1601 to 1607, Kiyomasa greatly expanded the castle, transforming it into a castle complex with 49 turrets, 18 turret gates, and 29 smaller gates. The smaller castle tower, built sometime after the keep, had several facilities including a well and kitchen. In 1610, the Honmaru Goten Palace was completed. The castle complex measures roughly 1.6 kilometers from east to west, and measures 1.2 kilometers from north to south. The castle keep is 30.3 meters tall.
The castle was besieged in 1877 during the Satsuma Rebellion, and the castle keeps and other parts were burned down. 13 of the buildings in the castle complex were undamaged, and have been designated Important Cultural Properties. In 1960, the castle keep was reconstructed using concrete. From 1998 to 2008, the castle complex underwent restoration work, during which most of the 17th-century structures were rebuilt.
The signature curved stone walls, known as musha-gaeshi, as well as wooden overhangs, were designed to prevent attackers from penetrating the castle. Rock falls were also used as deterrents.
In 2006, Kumamoto Castle was listed as one of the 100 Fine Castles of Japan by the Japan Castle Foundation. On December 7, 2007, a large-scale renovation of the Inner Palace was completed. A public ceremony for the restoration was held on April 20, 2008.
Within the vast grounds and unique architecture of Kumamoto Castle, many historical clues remain about how feudal lords lived during the Edo Period. Throughout Kumamoto, you can see many examples of the construction and architecture from those days, built with the latest techniques of the times, under castle master Kato Kiyomasa.
According to Wikipedia