Spiral staircase. Stressful to take on but very rewarding in the end. Falling down stairs like these almost seem pleasurable because you really get a great inside look at all the detail that went into such an installation.
Hey that is some good work! You know before the damn regulators and codes one could see some crazy good wood work on stairs. You still can still in some rural properties or, for example, if you go to Holland, Denmark, etc where they have these narrow houses with multifloors and the stair cases are crazy to twist around and get up with saving space. I once asked "how the F does an old person handle these" and the reply was: they move out. Like less than an inch on the inside and not, technically, spiral staircases. No codes about rise/run/nose etc, it seems!
ps: there is a mystery staircase in SF, New Mexico in some church. Supposedly some church needed stairs and a random carpenter came in and built it with no supporting column and in space to get up etc. Miracle they claim. Internet says "not so." They charge however to look at it, so I didn't, except peek in. Nice work, even if not a miracle.