Built from stone and wound in a clockwise direction if one was ascending, spiral stairs first appear in medieval times. This placed right-handed (more common) swordsmen attacking at a disadvantage. Because this asymmetry forces the right-handed swordsman to engage the central pike thus diminishing his weaponry stance. So the defender who is charging down the stairs holds the advantage.
Because they are compact, these staircases save space and are a great choice for modern times. The handrail is on the outer side with only a central pole on the opposite. And spiral stairs originate from different countries like France and England. Plus, there are different architectural styles like Victorian and Beaux arts. Finally, a great choice for a simple, sleek design.