Echizen Ono Castle had a large watchtower on the second and third floors with an observation tower in the main area and another smaller watchtower on the second floor. It also had multiple "Kuruwa"--districts limited by water, fence, or anything else. These districts were the secondary area of a castle (二ノ丸, Ninomaru) and the furthest outer area (三ノ丸, Sannomaru) at the beginning of the Kameyama mountain, connecting a canal and a river to protect the castle. It also had a stone wall (石垣, ishigaki) which is a wall or fence made by assembling stones, with a construction method called Nozora-zumi (野面積み), which is an old style stone wall piled up without processing natural stone. This is nowadays a valuable historic site. However, the castle tower itself has not been rebuilt after it was burnt down in 1795.