I've always heard that there are 3 Heavens. Here is what I was taught that they are:
First Heaven - First heaven is this world; Like heaven but corrupted.
Second Heaven - Second heaven is the celestial bodies: The sky, planets, stars, and universe (everything overhead).
Third Heaven - This is what we traditionally think of when we think of heaven. The third heaven is the dwelling place of God and the ultimate destination of some people.
I recently heard that there is more to the 3 Heavens than what is stated above in it's tame and naturalistic form. I heard that the realm of the "spirit" extends through all three Heavens. Thus when a soul dies, it first discovers that they have died while "in the spirit" (as in spiritual plane) here, the First Heaven. It is here in the First Heaven that a soul might have an angelic encounter and be carried to the Second or Third Heaven if saved. Essentially the Second Heaven is the abode of many classes of angels. And the Third Heaven is what we traditionally think of when we think of Heaven; a place where the very presence of God is manifest.
I found this thought provoking.