View of the Kiso River from the donjon of Inuyama Castle (Shot by Younghusband, Summer 2008)
_Chikujojutsu_, the Japanese art of fortifications, classifies castles into three main categories: _hirashiro_ (flat-ground castles), _hirayamashiro_ (hill castles), and _yamashiro_ (mountain castles).
The _hirashiro_ was usually the home of a lord and had a population centre connected to it. Being on flat land it was easily accessibile by the lord’s subjects. The _hirashiro_ was the most difficult type of castle to defend as siege towers could be erected providing an elevated position from which to attack from.
The _yamashiro_, on the other hand, was situated on the summit of a mountain, and was thus the most easily defended since there were a bounty of natural defenses such as cliffs and forests. The _yamashiro_ was also the least susceptible to the destructive power of earthquakes, which tended to ravage other kinds of plain-based structures. Unfortunately, they were difficult to construct. Digging for water supplies was particularly challenging. _Yamashiro_ were vulnerable to damage by strong winds and were also nearly inaccessible by citizens of the fief.
_Hirayamashiro_, built on a hill or low mountaintop providing a view of the plain below, had the most advantages and least disadvantages of the other types of castle since it mixed the properties of the yamashiro and hirashiro.
There are also rare categories of castle such as the _ukishiro_ (“floating castle”), constructed on small islands. This type of castle enjoyed an endless supply of water, and a natural moat preventing many siege tactics.
Last week I went on a tour of “Okazaki Castle”:http://en.wikipedia.org/wiki/Okazaki_Castle, rebuilt in 1959 and said to be the birthplace of Tokugawa Ieyasu. The second floor of the castle features a brilliant display of samurai weapons and armour. Although the castle is not in its original position, the following video from the top of the donjon gives you an idea of the view from a _hirashiro_.
Last summer I visited “Inuyama Castle”:http://en.wikipedia.org/wiki/Inuyama_Castle, which is one of Japan’s oldest extant castles. From the top of this _hirayamashiro_ one can see far across the plains of Gifu and Aichi prefectures. (Forgive the low res of the video, it was shot with my Sony digicam).
In all my time visiting castles in Japan I have never been to a _yamashiro_. However, I did see “Iwakuni Castle”:http://ja.wikipedia.org/wiki/ファイル:Kintaikyo_and_Iwakuni_castle.JPG while at the bridge where “Sasaki Kojiro”:http://en.wikipedia.org/wiki/Sasaki_Kojirō#Swallow_Cut perfected his _tsubamegaeshi_ technique. One day I will get to take some film from a donjon on top of a mountain.
Related: Some photos of “Nagoya Castle”:http://www.flickr.com/photos/younghusband/sets/72157604659287763/.