You can do something like in Google sketch up with some playing around. With GIMP, if you want an ISO view, you would likely have to hand draw it all yourself, so in this aspect, I am not quite sure what you question is...

As for Google sketch up, there are tons of pre created models, perhaps even some buildings you need if you are doing a specific university, plus you can change the angles at will which you can't do in GIMP/PS.