Trade posts benefit city vassals located in counties that have a trade post. This can even produce like >40% tax bonus.
Logically, there is no reason why the villages, towns and cities in castle/church holdings – Large Castle City etc. – shouldn't benefit from it too. Perhaps at a 50% rate due to government type issues.
Next, Europe's largest rivers are already flagged as navigable by the vikings. There should be some appropriate variables in the game to add a minor tax base/trade benefit from being located at such a river, nope? I'm not talking about full trade posts etc., but realistically such cities should be making more cash due to all the freight taking place over the river to the ports at the delta.
Logically, there is no reason why the villages, towns and cities in castle/church holdings – Large Castle City etc. – shouldn't benefit from it too. Perhaps at a 50% rate due to government type issues.
Next, Europe's largest rivers are already flagged as navigable by the vikings. There should be some appropriate variables in the game to add a minor tax base/trade benefit from being located at such a river, nope? I'm not talking about full trade posts etc., but realistically such cities should be making more cash due to all the freight taking place over the river to the ports at the delta.