Pysically growing cities

[ghen]

Expanding on the current idea of setting towns around cities, what if city graphics expanded after a certain population point to be 4 squares instead of 1? Doing this would be optional but would turn 3 people into perminant specialists to make up for the lost workable tiles, etc. The city would have better production, and maybe tourist money, but be less defenseable due to the larger number of surrounding tiles.

Just trying to think up fun ideas, though I have no will to impliment it