This article talks about several famous castles in Japan, including Kumamoto Castle and Edo Castle. Though the article doesn’t mention it, after Kato Kiyomasa built Kumamoto Castle he was involved in the construction of some of the stone walls (ishigaki) of Edo Castle. The following Japanese blog entry says that while stone walls in the Edo Castle complex that were built under the supervision of other daimyo (regional lords) crumbled when heavy rains hit Edo Castle, Kato Kiyomasa’s walls stood firm. The blog entry also explains how Kiyomasa’s engineering differed from that of his contemporaries.
http://blog.q-q.jp/201203/article_13.html
http://www.timeout.com.hk/travel/features/68440/castle-spotting-in-japan.html
