I first came across the City Metaphor in 2010/2011 when I was searching for a tool which could visualize code analysis models in 2D and/or 3D.
During this time I discovered CodeCity which was written in Smalltalk by Richard Wettel ( https://wettel.github.io/codecity.html) as part of this PhD thesis.
I used CodeCity for Java Projects. But at that time no .NET Famix generators exited which suited my needs. So I implemented a Famix generator for .NET which I sucessfully used to import models into CodeCity. This was so to say the starting point of SharpMetrics. I published an article about my tool and CodeCity in the german magazine dotnetpro in 2013: