I had some ideas on culture and borders:
Other than slowly accumulating culture, you should also be able to instantly gain a boost of culture, like in the Mesoamerica conquest. This would be happen after you built a culture producing building. There would be a chance every turn that something would happen at one of your culture improvements, say at the Colosseum, a Gladiatorial Tournament would take place, or at the Museum/Library improvement, a special exhibit or work would be on display. In later ages, Art museums would not only give massive 'accumulating culture', but would give a huge culture boost when a new gallery would be open.
Units passing through your territory, legally or illegally , should have the chance to be 'amazed' at your culture, and decide to drop everything and join your cause, without retaining nationality.
Castles should push borders back some. They should also make the nearest city accumulate culture faster.
Just a thought, you sould be able to build fences or walls around your borders to hinder unwanted transients. Gates would be placed on roads, and only your units and nations with RoP would be able to pass through. Trenches may also be a strategic plus.
Other than slowly accumulating culture, you should also be able to instantly gain a boost of culture, like in the Mesoamerica conquest. This would be happen after you built a culture producing building. There would be a chance every turn that something would happen at one of your culture improvements, say at the Colosseum, a Gladiatorial Tournament would take place, or at the Museum/Library improvement, a special exhibit or work would be on display. In later ages, Art museums would not only give massive 'accumulating culture', but would give a huge culture boost when a new gallery would be open.
Units passing through your territory, legally or illegally , should have the chance to be 'amazed' at your culture, and decide to drop everything and join your cause, without retaining nationality.
Castles should push borders back some. They should also make the nearest city accumulate culture faster.
Just a thought, you sould be able to build fences or walls around your borders to hinder unwanted transients. Gates would be placed on roads, and only your units and nations with RoP would be able to pass through. Trenches may also be a strategic plus.