While thinking about what 'Structure' concept to choose, I decided to look into 'Steampunk'.
A particular blimp design really caught my eye and fitted with the basic idea of number (33).
I had doubts that blimps would be classified as a 'Structure', however I found a quote from Wikipedia which states;
"Physical structures include man-made and natural arrangements. Buildings, aircraft, soap films, skeletons, anthills, beaver dams and salt domes are all examples of physical structures."
My favourites are; (2), (6), (7) and (8).