Very nice stuff. I can't wait until there are a few hundred people like you all going after a city or landmark.
I´m thinking of starting on some modules, if there is snapping/instancing/copy planned for object placement.
A castle can look very complex even with a mix of a few premade modules.
But not sure what is the best approach for collision etc?
Should be more effective then 1 large model I guess, but you knever know.