Poskær Stenhus is Denmark's largest round barrow, dating from the age of Funnelbeaker culture (around 3300 BC). The best view of this monument is from the north approach by the road through the hills of Mols Bjerge. The burial chamber has a diameter of more than 2 metres and a ceiling height of almost 1.8 metres. The chamber is surrounded by 23 kerb stones, some of which are more than 2.5 metres high. In 1859, the owner, Ole Hansen, started blasting the barrow stones to sell them as building material. He needed the money for his family and couldn't turn a proper living from the land where the barrow was. The barrow was rescued by local officials.
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.