Originally built during the Goryeo dynasty (918–1392), this fortress served as safety refuge for citizens during wartime. The fortress wall was built during the Joseon era and the fort itself was rebuilt in the 17th century. The 8km wall encircles the ruins of a Joseon archive, a reservoir and another temple, Anguk-sa.
There are three gates to the walled fortress, Bungmun (north gate), Nammun (south gate) and Seomun (west gate).