Seobukgangnu (서북각루) is the northwestern pavilion. The structure, known as a gangu, is located at an elevated position to allow surveillance of the surround area.
In times of peace, Seobukgangnu was used as a place of rest. During times of war, it was used as a command post by troops stationed near Hwaseomun Gate.
The first floor featured a floor heating system. This system was used by troops to keep them warm during the cold night duty.
There are a total of four gangu present at Hwaseong Fortress.