While on the subject of self-supporting roofs and unusual designs, I have to share with you all the story of this, possibly the largest and most original cob house in the world. While cob is a non-wood building material, the roof beams on this home are huge glulam timbers implemented in a roof design that you have to see to believe.
While the video is long (it is an episode from a British cable program), and it took me three days to find the time to watch the whole thing, I was smiling the whole time I watched. I can't even find words to comment on the effort...you have to watch it yourself.
Update: Looks like the video was posted to YouTube illegally, and has been removed. Click here for more information on the Cob Palace of Devon.