The Kitanomaru (北の丸?) is the northern enceinte next to the Honmaru. It was used as a medicinal garden (Ohanabatake) during the shogun's rule. During the 17th century, the Suruga Dainagon residence was located there as well, which was used by collateral branches of the Tokugawa clan. Today this site is the location of the public Kitanomaru Park. Not much is left from the times of the Edo Castle except for two gates, Shimizu-mon and further north Tayasu-mon.
Kitanomaru is surrounded by moats. The Inui-bori and Hirakawa-bori to the south separate it from the Honmaru and Chidorigafuchi to the west.
Read more about this topic: Edo Castle