I think it would be cool to have clan cities that could be upgraded by donations from members and upgrades chosen by leaders or coleaders. It could have a central clan hall and then you could add defenses and walls.
It would be present in your clan wars, it wouldn't attack obviously but if an enemy player attacked it and won it could be worth say up to 6 Stars instead of 3.
Anyways I think it would be cool because it would give clans something to build as a group.

