Hi there.
Right now building pretty and thought through towns or cities is not really possible, since you would have to place all cores perfectly adjacent to each other and every land owner then would need to give up space of there land for communal streets and stuff. This is not feasible and will end up in a total mess. Building with a huge core for the whole town is also not a good idea, since all inhabitants would need share everything.
What i think of may be for example a special core, that is large enough to be places overlapping with all the private cores of the town, but only allows building between the actual building cores and without having to give out rights to everyone. So one could fill up the in-betweens with roads and walkways and stuff.
See ya.