I tried to keep the scene as tidy as possible.
I divided the world into four different sections.
North, East, South and West platforms, with a bridge related to each. In the centre was a group for the Castle, forts, globe and base.
Underneath the bridge group, there was the platforms; Fort, Village, Farm and the City. Each platform then had buildings grouped to it.
I would have screenshot it, but my mac is struggling to open the file at the minute.