Dvergr spiral left stair is a buildable structure. It is a quarter-turn segment of a spiral staircase, ascending in a counter-clockwise direction. Multiple Dvergr spiral left stairs can be easily stacked in a rotating fashion to produce a spiral staircase of arbitrary height.
The Dvergr spiral left stair needs to be built within the range of a Black forge. There is also a mirrored version of this structure, the Dvergr spiral right stair, for building spiral staircases rotating in the opposite direction.