The January 2010 issue of the World of Interiors featured a stair that I just couldn't get out of my head; it looked so familiar. The Copenhagen police headquarters is a masterpiece of modern Neoclassicism from the 1920s that contains this gem.
This image looking up towards the skylight finally reminded me of where I had seen this before. Nature! 
The spiral stairs perfectly mimic the shape of a chambered nautilus shell. Does this prove that most beauty is derived from nature? Perhaps not, but it sure is an arguement for the statement!
Photographs from WOI, January 2010 by James Mortimer