These Abandoned Military Bases Will Leave You Speechless

Flak Towers

Built by the Nazis during WWII, these towers were used by forces to defend against air raids by the Allies. The walls were eleven feet thick and made from concrete, had radar within them and often rose ten to twenty stories above the ground. They also had multi-level guns built into them that could fire at a sustained rate of 8000 rounds per minute and had room for up to 10,000 civilians and an underground hospital.