Although being called "-dai" (meaning tei/house), Jurakudai was in fact a castle on a plain, since it included several enclosed areas such as a donjon with a castle tower in the center and a secondary enclosure around it, and was surrounded with a moat.
「第」（＝邸）とあるが、天守を持つ本丸を中心に二の丸などの曲輪を持ち、堀を巡らしており、実際は平城であった。