The Underground City of Beijing is a network of tunnels constructed beneath the city of Beijing, China. The complex is also known as the Underground Great Wall due to its purpose as a military defense system. The Underground City was built during the Cold War era as a bomb shelter to protect the civilian population from potential aerial bombardments.
The extensive tunnel system was designed to accommodate a large number of people and provide essential services during times of crisis. The construction of the Underground City reflects China's strategic planning and preparedness during the geopolitical tensions of the Cold War.