Most of bag 12 (bag 5 for the station) consisted of the roof.
Some of the largest pieces were warped (I haven't stored them in sunlight or near heat) and I had some trouble snapping them into place.
And don't be alarmed that I am spending between one and two hours per bag. I'm going slow, drinking coffee, listening to music, and enjoying myself. One reviewer put the entire thing together in seven hours.
I've put in 19 hours and I'm 2/3 of the way through.