For the great people of Oklahoma, the best of the best also live, work, and perform in OKC. OKC is also the capital (of Oklahoma). I won't touch culture because it's pretty pompous to assign culture to a single location. I'm sure the Sami people disagree with your location of the center of culture,
I'm not comparing cities and I certainly am not implying OKC is the same as Helsinki. Merely pointing out that the OP's comment about Helsinki being a large city with clean air sounded as silly to me as saying OKC is a large city with clean air.