My home has a circular staircase built by circling a telephone pole with 4X12 slabs of cedar bolted to the pole.  The outer ends of the treads are unsupported.  It undoubtedly was stunning while new but hasn't held up structurally over time.  At the top of the stairs is a catwalk suspended from the roof.  It, too, hasn't held up.  I won't bore you with what I had to do to reinforce things to keep them safe to use, but let's just say that a plain old staircase looks a lot better.  I would worry that this staircase might pull apart over time.  There's also the question of knowledge transfer as the house changes owners:  will the new owners know it's load-bearing capacity? What about shock loading from a kid jumping on the stairs?

The airiest stairway I ever saw was a very plain one that was proportioned and lit just right.