Sangdangsanseong Fortress is a historic site located in Chungbuk Province, South Korea. Built during the Three Kingdoms period, it served as a military stronghold to protect the region. The fortress features stone walls and various gates, showcasing traditional Korean architecture. Today, Sangdangsanseong Fortress is a popular tourist destination, offering scenic views of the surrounding landscape. Visitors can explore the well-preserved walls and enjoy hiking trails that lead to the fortress. It is also recognized as a cultural heritage site, reflecting the rich history of the area.