Namhansanseong is a historic Korean fortress city in Gwangju, Gyeonggi Province, South Korea. A UNESCO World Heritage Site, the fortress lies atop the mountain Namhansan and stretches 12 km in length. It served as an emergency capital city during the 1392–1910 Joseon period. The design is based on fortress architecture of East Asia, embodying aspects of four historical cultural styles: Joseon of Korea, the Azuchi-Momoyama Period of Japan, and Ming and Qing China.