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 s can be easily stacked in a rotating fashion to produce a spiral staircase of arbitrary height.
The 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.
ru:Винтовая (левая) лестница двергов
cs:Dvergské spirálové schody, levotočivé