I was reading the thread about bridge-building, and it brought to bear for me the fact that the world of the game would be a lot more interesting if there were kinds of structures other than just villages.
For example,
- Primitive bridges
- Hill forts
- Burial grounds
- Giant's churches
- Various forms of cairns
- Ceremonial/sacrificial sites
- Quarries, iron foundries
As far as hill forts go, I was also reading about the Old Castle at Lieto, and about how there would have been a watchtower, and it also made me think back to the issue of multi-story buildings.
Something that's currently not listed on the long term development plans, but I would certainly like to see as a player, is a revamp of the game system for creating interior spaces. So for example, on houses, this would mean that when you see a house from the outside, you see the building height, the roof on top and smoke from the chimney. You go inside, and you see the floor you go in on, and then can go up and down floors if its multi-story. You could even go down into cellar basements. Sort of how old isometric games like Ultima VII handled it. This would also lead to a better game system for caves, because they could actually be inside mountains and hills rather than inside a group of stones.
While I'm guessing this is definitely require major work compared to other game features, I think it would be something worth seeing.
Also, I don't know if any evidence of this exists for Iron Age Finland, but I know that in other areas, there were stone buildings in forts.
In general, I think the more that there's variety in structures, the more there will be a feeling that you're in a world with a history, and that would also tie into quests and things like that.