This is a typical defense fortress wall surrounding the basin of the cliffy mountain. After the invasion of the Khitan during the late Goryeo Dynasty, General Choe Yeong proposed the building of a fortress and a storage here; Choe Yun-deok, an inspector during the reign of the Great King Sejong, also insisted that this place is worth protecting for its strategic importance. This fortress wall is believed to have been built in the late Goryeo, based on the fact that the people near this fortress took shelter in it during the aggression of the Khitan in the Goryeo Dynasty and Japan in the Joseon Dynasty. Jeoksangsan Archives, one of the five representative storehouses for history books built by the order of King Gwanghaegun, keeps Joseon wangjo sillok (Annals of the Joseon Dynasty) as well as the royal family pedigree of Joseon. Sillokjeon Hall, Sagak and Seonwongak (archives for historic books), armory, Daebyeolgwan Hall, and Hoguksa Temple were built near it. After the Japanese Invasion of Korea in 1592, the fortress was downscaled. Today, the wall has practically collapsed, and we can see only parts of it remaining in the forests. The buildings including Sagak are gone, and only the sites and Anguksa Temple remain.