I've heard that the second Vatican council eliminated the concept of limbo. Or maybe that it never existed to begin with.
Was limbo part of "official" Catholicism before Vatican II? What changes were made at Vatican II regarding limbo?
The origin of limbo is actually the place where the Saints that came before Jesus “waited”. This is what the Apostles' Creed speaks of by calling it the dead:
And the CCC clarifies this and uses the term abode of the dead:
The hypothesis that was abandoned recently implied that children who died unbaptized would go to that same place.
And to answer your other question: I found no mention of the term Limbo (Latin: Limbus) in any of the official Vatican II documents using Google. (All the documents are there and indexed you can verify) So maybe they just didn't treat the subject.
If you look at this question, you will find references to statements by Benedict XVI regarding Limbo. Specifically he says:
If Limbo was never a doctrine of the faith, then Vatican II cannot have 'eliminated' it. In short, Limbo was only ever a theory, and is less popular these days than it was.