Where have they all gone? To underground cities

Wh-what . . . a . . . w-world . . .

Underground city

https://en.wikipedia.org/wiki/Underground_city

News Articles

Why 1 Million People Live in Cold War-Era Bunkers Under the Streets of Beijing

In Beijing, anywhere between 100,000 to one million people live underground in old bomb shelters. Dubbed the shuzu, or “rat tribe,” these subterranean citizens occupy a cramped, musty, and windowless world located dozens of feet below the bustling streets of China’s capital city. This extensive network of largely illicit bunker housing is unlike anything found in any other major metropolis in the world.

The roots of Beijing’s invisible underworld were laid during what could be called the other Cold War.

http://mentalfloss.com/article/563950/why-1-million-people-live-underground-beijing