The Paris Sewer Museum!

 Yes, there really is such a thing, as well there should be!

https://www.tpomag.com/online_exclusives/2015/09/this_sewer_museum_stinks_but_its_worth_the_visit?ref=popular_bottom

Here are some videos!

https://video.search.yahoo.com/search/video;_ylt=Awr9GjDiy6hgz8YAkfpXNyoA;_ylu=Y29sbwNncTEEcG9zAzMEdnRpZAMEc2VjA3Nj?p=paris+sewer+museum&fr=yset_chr_syc_oracle#id=6&vid=3b16b0d12be7051ab2b221e5e11a253d&action=view

Brussels has one too, although it looks to be more sanitized and not a smelly as the one in Paris looking at the reviews.

https://sewermuseum.brussels/en/accueil-english/the-museum/

Enjoy!