Purgatory!
If Hell Is Down And Heaven Is Up, Then What's In The Middle?
Earth. The ground where us humans are.
The up and down representation is really not very accurate to the actual idea. "Up" in much of Canada would be considered to be "down" in Australia. It's only figurative really, the religious types just wanted to make completely sure that you knew heaven was superior and hell was bad so that you definitely would not want to go there and believe.
You.
San Fransisco.
Purgatory, and Limbo.
Maybe it's the earth