Flossenbürg was a Nazi concentration camp built in May 1938 by the SS Main Economic and Administrative Office. Unlike other concentration camps, it was located in a remote area, in the Fichtel Mountains of Bavaria, adjacent to the town of Flossenbürg and near the German border with Czechoslovakia. The camp's initial purpose was to exploit the forced labor of prisoners for the production of granite for Nazi architecture.
In 1943, the bulk of prisoners switched to producing Messerschmitt Bf 109 fighter planes and other armaments for Germany's war effort. Although originally intended for 'criminal' and 'asocial' prisoners, after Germany's invasion of the Soviet Union, the camp's numbers swelled with political prisoners from outside of Germany. It also developed an extensive subcamp system that eventually outgrew the main camp.
Before it was liberated by the United States Army in April 1945, 89,964 to 100,000 prisoners passed through Flossenbürg and its subcamps. Around 30,000 died from malnutrition, overwork, executions, or during the death marches. Some of those responsible for these deaths, including administrators, guards, and others, were tried and convicted in the Flossenbürg trial. The camp was repurposed for other uses before the opening of a memorial and museum in 2007.
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.