My favorite is Detroit and their absolutely ridiculous approach to planning the city, which was along the lines of “hue hue hue hue let’s make it look like a wheel and spokes!!” then only a decade later “hmm wait never-mind”, leading to an awful mishmash of design ideas resulting in a downtown that is basically impossible to drive. Luckily, no one really goes downtown in Detroit since the riots in the 60s, otherwise the traffic would be terrible.

https://detroitplanninghistory.weebly.com/1700-1900.html

This was fun too: https://panethos.wordpress.com/2020/11/22/the-worst-failures...

They also displaced whole neighborhoods to build highways and bridges https://www.luc.edu/eminent-domain/siteessays/detroitmi/

Add in the collapse of the American auto industry that was keeping Detroit relevant and these days it all adds up to be a place I never see myself going back to in this lifetime, and an example of how bad in so many different ways a city can be.

Bonus: they have an above-ground train that goes between places no one actually ever goes between https://gizmodo.com/i-spent-a-day-on-the-world-s-most-pointl... it’s like if BART went between the SAP Center and Levi’s Stadium with no other stops.