Unlike many other cities in China, Beijing has a long history that spans thousands of years. For the past few centuries, it has been the political center of China and the focus of its people nationwide. Because of its rich history, the underground situation in Beijing is extremely complex, filled with secret tunnels and subterranean structures everywhere.
However, these subways and buildings exist independently of each other and are not interconnected. Apart from a small portion that has been discovered and utilized, many more such projects remain unknown, still hidden beneath the city.