Old "sewers" are so enormous...

[Soretna]

I recently saw a photo of old sewer works under Newark New Jersey that was supposedly built in the 1920s. Something about them being 22 miles long and with 18 miles of branch sewers is somehow difficult for me to believe when one sees a picture:

From the "lovely" Smithsonian:

These Photos Capture the World's Sewer Systems When They Were Brand New