Takamatsu Castle - Credit: Wikimedia Commons
of Bitchū Province was a Sengoku period Japanese castle located in what is today the Kayo neighborhood of Kita-ku, Okayama in Okayama Prefecture. The style of the castle was a hirajō (flatland castle) with no stone walls, but only earthen walls. The castle was surrounded by marshes, which formed a natural moat. Its ruins have been protected by the central government as a National Historic Site since 1902. Read more on Wikipedia
Source: en.wikipedia.org