The mound was solidified with clay and a wooden or stone tower (keep) was built on top of it, and the knoll was surrounded with a wooden outside wall to create castle facilities, such as warehouses and houses.
小山は粘土で固めてその頂上に木造または石造の塔(天守)を作り、岡を木造の外壁で囲んで、貯蔵所、住居などの城の施設を作るものである。