For example, it would seem there was nothing out of the ordinary regarding the underground parking lots of shopping malls or residential areas except for the heavy lead-grey iron doors at its exits. However, that would indeed make it part of a civil air defense project. It could be used as an air-raid shelter or temporary refuge in event of a foreign invasion or nuclear war.
Doomsday Bunker Upgrade
Sci-fi · Seventeenth Zither
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