Stairs have 1 magnet in the base. It attaches to the floor piece or surrounding curved wall (see pictures). It fits nicely inside 2-3 1x1 Curved Walls: https://www.prusaprinters.org/prints/43608-wall-cut-stone-curved-1x1-diagonal
There was some roughness at the bottom of the stairs when you print them without support. For me that was no problem.
I found multiple stairs in Thingiverse.com. All different prints, different sizes,.... This version allows again more flexibility with existing curved wall pieces.
The author hasn't provided the model origin yet.