Ah.. In that case i have a suggestion.

You could use voronoi diagrams. Check:

http://en.wikipedia.org/wiki/Voronoi_tessellation

You can implement an algorithm (like the sweep line algo here):

http://en.wikipedia.org/wiki/Fortune%27s_Algorithm

It takes a set of center-points and divides the space into regions. Each region has one center. It creates nice mosaic patters. You may want to use this. You could let the regions be the building, parks or whatever and the borders between the regions could be the roads.

I would like to implement this myself one day.

Hope this is usefull.