Basic design for castle construction is called nawabari (castle plan; general term for the layout of a castle and its component structures) or keishi and the most important element is arrangement of Kuruwa (walls of a castle).
築城に際しての基本設計を縄張（なわばり）あるいは径始・経始（けいし）といい、その中心は曲輪の配置にあった。