The height of the "Ni-no-kuruwa", which is an elongated L-shaped "kuruwa", is 17–18 metres (56–59 ft.) above sea level with the dimension of about 310 metres (1017 ft) from north to south. This "kuruwa" was designed to defend the gates of the "hon-maru" and functioned as a key "kuruwa" which controlled access to the "hon-maru" through its many gates. This "kuruwa" is well fortified; for example, it had a "kakushi-guruwa" (a hidden "kuruwa"), which was located to the south of the Kirinoki-zaka Gate and used for laying an ambush against an approaching enemy. Depicted in some old maps are several "yaguras" and something like a hitching post stable, but there are no other buildings, such as a residence complex.