Additionally, a number of remains of buildings were discovered around 'Mt. Bingushi' situated between 'Second Castle Door' and 'Third Castle Door' whereby it is considered that a major facility such as lodging houses for Sakimori (soldiers garrisoned at strategic posts in Kyushu in ancient times) existed in that area.
また、「二の城戸」と「三の城戸」の中間に位置する「ビングシ山」周辺から複数の建物跡が発見されており、防人宿舎など中枢機能があったと考えられている。