The Zytglogge is a landmark medieval tower in Bern. Built in the early 13th century, it has served the city as guard tower, prison, clock tower, centre of urban life and civic memorial.
Despite the many redecorations and renovations it has undergone in its 800 years of existence, the Zytglogge is one of Bern's most recognisable symbols and the oldest monument of the city, and with its 15th-century astronomical clock, a major tourist attraction. It is a heritage site of national significance, and part of the Old City of Bern, a UNESCO World Cultural Heritage site.
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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.