Liptov castle is the highest situated castle in Slovakia, located in the height of 993 metres. The first written record about the Liptov castle comes from 1262. Liptov castle was a royal castle in the past and its duty was to protect the borders of the country. Now you can admire the beauty of Liptov from there, but also rich archeological exposition in the nature.
References: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.