Multiple Capitals

In the case of larger empires it wasn't unknown to have two major cities acting as capitals for different halves of the empire. The most famous example of this is of course Rome, with Constantinople, which occurred out of the time frame. However, the Seleukids did a similar thing, with Antioch acting as a sort of western capital and Babylon then Seleukia-on-Tigris being seat of rule for the east; this case is mainly argued by Kuhrt and Sherwin-White, and is supported by examples of a sub-ruler governing half of the empire while the king is in the other half in the case of Seleukos I and Antiochos I and the whole Stratonike thing, then again in the Maccabees with Antiochos IV and the regent Lysias. I don't know about the Parthians and Sassanids, but it seems unlikely that Ctesiphon, so far west, was the only big administrative centre of their predominantly eastern empire; it seems more likely it was the only one the Romans had any real contact with.

If it's possible to code, could factions be allowed a second or sub-capital for the purposes of working out distance to capital penalties and/or corruption once their empire grows beyond a certain point? Given that at least two of the empires big enough to warrant it settelde eventually (if with debatable success) on this solution, isn't it quite plausable that in the same circumstances other factions may have done the same?

I'm pretty confident that such a feature would be impossible to do in M2TW due to the hardcoding.

What a pity!
That would be nice for major empires (and huge cities).

I guess if it could be implemented as a special building.

parthians used ctesiphon as their main capital , they used also ecbatana(modern hamadan) and susa as summer capital because of the helly conditions in mezopotamia...

yes romans used many of them before falling they used mediolanum (milan) as their military capital also ravenna was used by latest western roman empires as the seat of the throne..

sassanids followed parthians in the same way....

We have been pwned by the hardcode! /singsong-voice

Pwned by the hardcode. Sounds pretty good.