I don't know of any place that is mouse proof, but you can always set mouse traps and in some places I think you can still use mouse/rat poison. Only thing is, if you poison the little buggers they may die in places where you can't get to them to remove their decaying carcass. Also, by using poison you may accidentally kill off a family pet, which probably would not be a good idea. Still, if you don't have pets and if there are no "out of the way" places where the mice can be when they die, poison MAY be a viable option.