jangmisanseong (장미산성)
This fortress is thought to have been constructed by Goguryeo during the Three Kingdoms Period, potentially the farthest south of any fortification built by that kingdom. It was later occupied by Baekje and Silla in succession. Built along a steep ridgeline overlooking the Namhan River, this site would have provided control over access through the northern approach to Chungju and the fertile Han River Valley so coveted by all three Korean kingdoms.