Børsen (The Stock Exchange) was built by Christian IV in 1619–1640 and is the oldest stock exchange in Denmark. It is particularly known for its Dragon Spire shaped as the tails of fourdragons twined together, reaching a height of 56 metres.
Christian IV had ambitions to turn Copenhagen into a metropolis and to strengthen the city's position as a commercial centre, he wanted a stock exchange along with the new merchant town Christianshavn he was constructing on the other side of the harbour. He asked Lorentz and Hans van Steenwinckel the Younger to design a building in Dutch renaissance with 40 small stalls at the ground floor and one big room at the upper floor.
The building was restored by Nicolai Eigtved in 1745 and internally renovated in 1855. It housed the Danish stock-market until 1974. In 1918, unemployed anarchists attacked Børsen, an attack that went to the Danish history books as 'stormen på Børsen' (the storm at the stock exchange).
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.