Beijing Underground City

The Beijing Underground City, also known as the Underground Great Wall, is a vast network of tunnels and chambers located beneath Beijing, China. Built during the Cold War era for military defense purposes, this subterranean complex served as a bomb shelter and a means of transporting intercontinental ballistic missiles (ICBMs). Spanning over 3,000 miles (5,000 km), the Underground Great Wall is an extensive system that highlights China's historical preparedness for potential nuclear conflict. Today, while some portions of the underground city have been repurposed for tourism, much of it remains closed to the public.