Does any one know how to change city set graphics?

[ghost toast]

i would like to add more diversity to the look of cities.
i can easily come up with some diverse cities models but how to i get them into the game?
please some one help me.

 

[ghost toast]

i have managed to at least make invisible cities. maybe it can be populated by making the city sets that will actually be a wonder that replaces a free building every city can get when settled.

 

[ghost toast]

graphic testing is yielding results