Absurdly Spacious Sewer - TV Tropes
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When an urban sewer system is large enough to serve as an underground lair, be it a single dwelling or a colony serving an entire community. Realistically speaking, most modern sewer systems consist of pipes too small for an adult to enter. They …

Literally every sewer in every video game, cartoon, anime and even some movies.

I was thinking today about drains for some reason and how in reality they’re like only a couple inches wide.