Finnish fortifications refer to the military structures built in Finland to defend against invasions, particularly during the Winter War and Continuation War against the Soviet Union. These fortifications include bunkers, trenches, and artillery positions, strategically placed to utilize Finland's rugged terrain. One of the most notable fortifications is the Mannerheim Line, a series of defensive fortifications along the Karelian Isthmus. Constructed in the 1920s and 1930s, it featured concrete bunkers and anti-tank obstacles, playing a crucial role in Finland's defense strategy during the conflicts of the 20th century.