I think most US cities are like that in the “downtown to disheveled in 15 minutes” sense.
But that said, check out this completely empty block on Delmar and 21st [1], and remember that with the Arch, that's less than 20 blocks from the river. And five blocks north of there is the former site of Pruitt Igoe, which is basically six or so blocks of wilderness behind a chain link fence. I don't doubt there are cities in worse shape (Detroit probably being one of them), but none that I've explored.
Ive been everywhere in the US but the Dakotas and never seen a city of STL’s size feel so big yet so empty.