Cosmopolitan Oslo?
 

I'm reading a new mystery set in Oslo. It says that Oslo used to be just a provincial city but now is a cosmopolitan city. Is this true?

Yes.

You asked the same question on another thread about Copenhagen. I was in both Oslo and Copenhagen earlier this year and IMO both of these are cosmopolitan cities, but maybe we have different ideas of what "cosmopolitan" means.

Nothing provincial about the waterfront build up of the last ten years.