While castle towers were built on small hills or mountains with a good view of the surrounding areas, structures such as soldiers' residences were constructed on flatland near ports: in order to defend the area between the castle towers and soldiers' residences, Japanese style stone walls (ishigaki) were constructed from flatlands to hills and mountains, finally surrounding the main castle.
天守は、見晴らしの良い小高い丘や山にあったが、兵の居住建物等は補給口に近い平地にあったため、その間の防備のため、丘や山に石垣を登らせるように本丸まで取り囲む日本式の石垣を築造した。