I definitely think the Gate of All Nations should be the Persian Wonder. We'll keep the Hanging Gardens of Babylon for either Atlas purposes or some kind of "capture the monument" gametype.
http://www.persepoli...all_nations.htm
Stairs:
Front Gate:
Back Gate:
This is very handy.
It seems clear now that the Apadana should be upgraded to the Wonder. The columns are more visible than I thought (had to see the building from an "RTS" angle to make sure). The current Apadana special building could maybe be renamed to Tachara and still used for its current purpose or relegated to an Atlas structure.