The Rust Belt in general has left more interesting ruined urban settings that Silicon Valley will when it inevitably declines and empties out. Glass curtain wall office structures and styrofoam-detailed-stucco-sided McMansions won't leave much in the way of artifacts. Maybe it can go back to supporting prune orchards if they can get a little water.
There's a certain kind of nostalgia invoked when one sees pictures before and after comparison like these (even if most of us weren't alive or very young then). Sure tech wasn't that advanced back then but man you can see the love of life in those pics. No woke shit, no confusion, no screens (except stationary at home), no hobos and druggies and thugs (sure there always were some but they were fought hard), 2 genders and love for life lol.
The primary cause was automobiles plus increasing levels of black crime as black people moved north after WWII. This is sad but true.
And they fed on each other. People wanted the steel protection that cars offered from being assaulted.