Abstract: A winding stair for spiral ascension within a building structure. The stair includes a newel post which has a plurality of elongated slots horizontally formed around the periphery at different elevations. Each steps of the winding stair is provided with an arched end plate located along an inner narrow end of the step. With each arched end plate formed to hug the outer surface of the newel post. A curved flange portion extends upwardly along a top edge of the arched end plate. Steps are attached to the newel post as by inserting the curved flange portion within the elongated slots and allowing the arched end plate to rest against the periphery of the newel post. Aligned openings in each of the newel post and arched end plate, receive fasteners to secure the step to the newel post. The curved flange also has openings aligned with openings in the newel post receiving fasteners which serves to further secure the step to the post.