Kyminlinna fortress was part of the South-Eastern Finland fortification system built by Russia after Russo-Swedish War of 1788-1790. Kyminlinna and Ruotsinsalmi sea fortress formed together a defense line, which was planned to stop enemies attacking from the west. First fortress was a bastion constructed in 1791-1795 by the general Aleksandr Suvorov. The older part was replaced only couple of years later by the much bigger five-corner caponier fortress (built in 1803-1808). When Russia occupied Finland in the Finnish war, Kyminlinna lost its defensive status. Only real battle in Kyminlinna was fought in the Finland civil war (9.4.1918) between German forces and red guards.
Nowadays the fortress area is owned by the Finnish government and it's open for public.
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.