While I live in a one-story house, I find myself infatuated with interesting staircases. Here are two beauties:
From
Kelly Wearstler's home (featured in Metropolitan Home)

It's almost got an
MC Esher vibe - which way is up?
Loving these riser-less stairs that project out from the wall - though I might get vertigo going down them!

By
Hufft Projects - also from Met Home.