The Good Ol' Flag Issue

[Sirotnikov]

You could also have city flags, regional (county/state/region, etc.) flags.

Each party/guild could have its own flag. Each military unit.

The lists are fairly open for possibilities; Flags for Wonders, Improvements.

Each Minister or other official (elected, military, or appointed) could have their own flag, heraldry, or other symbol of office.

It wouldn't have to be limited to flags, the heraldry or symbols work equally well for some of the groups I mentioned above.