Heaven is hell depending upon one's expectations and attachments. A Psalmist once said “If I ascend up into heaven, thou art there: if I make my bed in hell, behold, thou art there” Psalm 138:8. Hell then is Heaven.
Where is heaven and hell? Up above? or Down below? Heaven and hell is wherever we make our bed and perhaps who we share our bed with. Presence is always Present which is our Present. Tat Tvam Asi — Thou art that!