And that means the Wall should be a Stokade upgradeable to a partly stone wall.
The Stone Tower should be partly wooden upgradeable to an all stone Tower and dimension of the Tower should be increased so that the diameter is the same as the gable of a house and the height should so high that the parapet is higher that a two-story house - right now it looks like a Well build the wrong way.
The Keep should be a partly stone Mansion two-story building upgradeable to an all stone building.
The Tower and the Mansion should be able to connect together.
The Watch Tower should be all wooden upgradeable to be partly stone build and with a way to get up into it!
It would be nice if the walls could be build at an angle that way the player could build a Motte-and-bailey used in Britain, Ireland and France or a Ring fort used in parts of Scandinavia at the time of the Viking era.