Possible to retire in Berlin?

Dear Expats,

My wife and I are retiring (Finally!) and want to live in Berlin. We've lived in Germany several times and I speak German to an intermediate level (as defined by the Volkshochshule). and we have the resources to support ourselves. Is there anyone out there who has retied to Berlin and gotten residency without a German wife or claiming to be self-employed? Although the official websites are explicit about the issue, stating the Residence Permit is only issued for specific purposes, (study, rejoining family, employment, humanitarian reasons), there are articles on the web that claim it is possible to get a Residence Permit if you have sufficient resources to support yourself and do not try to work. Do you know anyone who has actually done this?

Appreciate your help!

Brian