Flak Towers were massive anti-aircraft fortifications built by Nazi Germany during World War II. Constructed in major cities like Berlin and Vienna, these towers were designed to protect against Allied air raids. They featured heavy artillery, radar systems, and bunkers for soldiers, making them formidable structures. Each Flak Tower was made of reinforced concrete and could withstand bomb attacks. They served not only as military installations but also as shelters for civilians during air raids. After the war, many of these towers were abandoned, while some have been repurposed for various uses in modern times.