The Underground Great Wall is a gigantic subterranean network in China.
In the earthquake of 2017, the weapons bunkers which were between Shaanxi and what would become the rump state of the Republic of China were sealed and a few nukes within detonated. Which has contaminated the region with radiation.
Those weapons bunkers were part of the "Underground Great Wall" of China which was built during the Cold War. An extensive network of tunnels and bunkers that was 5,000 km long (3,000+ miles). Which housed nuclear weapons, fissible material, ballistic missiles, and the vehicles to transport and launch those missiles. They were built hundreds of meters beneath the surface, within mountain ranges. Tunnels that had roads or rail lines connecting them. It was suspected that within that network were also command and control facilities and logistical support.
The network of bunkers and tunnels stretched from Xi'an in southern Shaanxi to the northeastern region of Beijing and Tianjin. A large cluster was centered in the southeast in eastern Yunnan, western Guizhou, and western Guangxi. A smaller cluster was in southwestern Manchuria in the Liaoning region adjacent to the Korean peninsula. There were also clusters in the Tibetan plateau, one around Lhasa in Tibet and the other one in the northeastern region of Qinghai.
China also built a network of over 40 subterranean air bases, which some considered part of the Underground Great Wall. Massive subterranean air bases that were built in mountains and were adjacent to airfields or standard air bases. Within were stored squadrons of fighter aircraft, attack aircraft, and sometimes even bombers. These bases were built mostly across China proper (the region south of the Great Wall and west of Tibet) and in Manchuria. In addition during the Cold War, like the Soviet Union the Chinese likewise built underground civil defense bunkers in their major cities, the greatest of which was Beijing's Underground City which some consider part of the Underground Great Wall. There were also two underground submarine bases which were built within coastal mountains, one in the province of Qingdao across from Korea and the other on the island of Hainan across from northern Vietnam, the latter of which can hold up to 20 submarines.
With such a vast network of tunnels and bunkers, it's a certainty that parts of it are still in use or salvageable. Likely used by the successor governments (most likely by the military) and the corporations (e.g. storage, research & development, etc). Like in other parts of the world, metahumans are likely to have taken over some of them and established their own subterranean communities, particularly the the dwarves, orks, and trolls.
- Shadows of Asia p.39
- Shadows of Asia, 39
- Wikipedia: Underground Great Wall of China
- Washington Post: Subterranean Nuclear Storage System
- The Bulletin: Underground Great Wall
- Jamestown Foundation: Underground Great Wall and Nuclear Deterrence
- Air Power Australia: Assessing PLA Underground Air Basing Capability
- Business Insider: Chinese Underground Air Bases
- Air Power Magazine: The Dragon Pours Concrete