The Salpa Line is a massive line of defensive fortifications approximately 1200 km long that was built in 1940-41 and in 1944 in order to defend the Eastern border of Finland.
The Salpa Line Museum in Miehikkälä is a museum on military history established in 1987 displaying the history of fortification works of the Salpa Line. The permanent exhibition of the museum consists of the exhibition and multimedia shows at the museum cafeteria and of guided tours to the fortifications on the outdoor museum area.
The Walls of Constantinople are a series of defensive stone walls that have surrounded and protected the city of Constantinople (today Istanbul) since its founding as the new capital of the Roman Empire by Constantine the Great. With numerous additions and modifications during their history, they were the last great fortification system of antiquity, and one of the most complex and elaborate systems ever built. They were also the largest and strongest fortification in both the ancient and medieval world.
Initially built by Constantine the Great, the walls surrounded the new city on all sides, protecting it against attack from both sea and land. As the city grew, the famous double line of the Theodosian Walls was built in the 5th century. Although the other sections of the walls were less elaborate, they were, when well-manned, almost impregnable for any medieval besieger.