Does anybody know if... (city flipping)

[Jperkinson]

Does anybody know if newly captured cities will spontaneously flip back to their original nationality? And if that does happen, does it still wipe out your stack of fortified troops like it used to in Civ 3? I used to hate that.

 

[Eyemaze]

it is an option in custom games you can enable.
Int he "play now" games it is off by default.