@One Eyed Mind,
Heaven was written into scripture to describe two things, one is the realm above, namely the sky, space, anything over our heads was described as the heavens. It is also used to describe the dwelling place of God. but we also know that flesh and blood cannot enter into the kingdom of heaven, so it is not a physical but a spiritual realm.
I often consider the "flatlands" principle as to how a spirit place could exist without our perception of it.
As for hell, as previously mentioned, hell is not in the bible. The concept of hell was adopted from outside cultures.
Hades/She'ol were written into the bible as standard terminology used by the people of the time to describe "the grave"
Gehenna was a physical place, it was on the map and so it was as natural to write in Gehenna as it would be to write in say Tyre or Si'don
Is there anything in the bible you consider to be literal rather than allegory or do you assert that everything is a metaphor for the universe and beyond?