Rundkirker, or round churches, are unique architectural structures primarily found in Denmark and Sweden. These churches, built during the late medieval period, feature a circular design, which was both practical for defense and symbolic for Christian worship. Their thick walls often served as fortifications against invaders. The most famous rundkirker include the Lund Cathedral and the Helsingør Round Church. Inside, they typically have a central altar surrounded by a circular nave, allowing for a communal worship experience. The design reflects a blend of Romanesque and Gothic styles, showcasing the historical significance of these buildings in Scandinavian culture.