clause with "where"

Here is the question sentence: I've got a slim friend from London where is the financial center of the UK.

I just feel confused about the word "where". Is it right? Or should I change it for "which".

Many thanks.


Which is better (describing London as the financial centre of the UK).

If you want to consider the City of London district as being the actual financial centre, it would be possible to say London, where the financial centre of the UK is.