There is a Kensington in pretty much every major US city today.
Yep...There sure is...Portland, Chicago, San Francisco come to mind...
I always felt every big city should have a certain area cordoned off with a high wall where anything goes. Drugs, gambling, prostitution. A guarded entrance at one end and a morgue at the exit. Maybe even a Thunderdome for gang shootings.
Keeps the riff-raff off the main streets away from decent people.