About Istakhr and "the Site of Persepolis", I was wondering if we could create a similar but smaller effect than there is between Memphis and "The Great Pyramid" in Egypt. This could include Persis and maybe some other Iranian regions next to Istakhr.
For instance "The restoration of Persepolis as a goodwill gesture increases the loyalty of noble Persians to the owing Faction regardless of culture".
This should motivate the Seleucids to defend it against any attackers and upgrading "The Site of Persepolis" helps management especially in Persis. Naturally Parthia, Baktria, and Armenia have equal desires to capture Istakhr in their own campaings...
Luc.