If you watched Paradise and thought an underground city of 25,000 people was too unrealistic, go visit Derinkuyu in Turkey: an 18-level, 85-meter deep underground city carved into rock that once hosted 20,000 people.
Discussion
And just look at Zion in The Matrix. They had that big-ass rave down there. I'm a believer.
The Nazis protect themselves from cosmic radiation this way. Their bases are buried deep in the lunar soil. About 14 million people already live there.
Apparently all of Switzerland was preparing to live underground at some point!
https://en.m.wikipedia.org/wiki/National_Redoubt_(Switzerland)
But did they had trees and vehicles down there?
*I only seen the trailer.
And they even had room for the cattle. Incredible.
There's a hard cap of 21,345 people for underground cities.
Spec for cosmic radiation from CME event, coronal mass ejection. Cyclical every 6000, 12,000 years. Also could be invading army protection but stone doors wouldn't have stopped battering ram. My question, airflow?