Spiral staircase to attic. Library Company of Philadelphia, Philadelphia, PA. Spiral stairs wind around a newel (central pole). They typically have a handrail on the outer side only, on the inner side just the central pole, and are often very steep. A pure spiral assumes a circular stairwell and the steps and handrail are equal and positioned screw-symmetrically. A tight spiral stair with a central pole is very space efficient in the use of floor area. A squared spiral stair assumes a square stairwell and expands the steps and railing to a square, resulting in unequal steps. Historic American Buildings Survey, undated (cropped and cleaned).