Sion is a small castle ruin in Chlístovice in the Central Bohemian Region of the Czech Republic. It lies near Kutná Hora. It was founded between 1426 and 1427 by Hussite Jan Roháč of Dubá. After a successful four-month siege the castle was conquered and burned by Emperor Sigismund's allies in 1437. Today, only scattered parts of the basement stone walls with some arches and stairs remain of the original castle.
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.