Fort Thüngen is a historic fortification in Luxembourg City sited in Dräi Eechelen Park. Named after the Austrian commander-in-chief of the fortress, Baron of Thüngen, it was built in 1732 to enclose the defence work called Redoute du Parc (Park Redoubt) set up by Vauban 50 years before. A deep moat surrounded Fort Thüngen which was accessible only through a 169-metre long underground tunnel through the rocks from Obergrünewald. In 1836 the Prussians extended the Fort and in 1860 strengthened it again.
Most of the original fortress was demolished after the 1867 Treaty of London, which demanded the demolition of Luxembourg City's numerous fortifications. The three towers and the foundations of the rest of the fort were all that remained. During the 1990s, the site was reconstructed in its entirety, in parallel with the development of the site for the construction of the Mudam, Luxembourg's museum of modern art.
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.