Stairs
Historic uses

The earliest known helical staircases appear in Temple A in the Greek colony Selinunte, Sicily, to both sides of the cella. The temple was constructed around 480–470 BCE.

When used in Roman architecture, helical stairs were generally restricted to elite luxury structures. They were then adopted into Christian ecclesiastic architecture. During the Renaissance and Baroque periods, increasingly spectacular helical stairways were devised, first deleting walled enclosures, and then deleting a central post to leave an open well. Modern designs have trended towards minimalism, culminating in helical stairs made largely of transparent glass, or consisting only of stair treads with minimal visible support.

There is a common misconception that helical staircases in castles rose in a clockwise direction, to hinder right-handed attackers. While clockwise helical staircases are more common in castles than anti-clockwise, they were even more common in medieval structures without a military role, such as religious buildings. Studies of helical stairs in castles have concluded that "the role and position of spirals in castles... had a much stronger domestic and status role than a military function" and that "there are sufficient examples of anticlockwise stairs in Britain and France in to indicate that the choice must have depended both on physical convenience and architectural practicalities and there was no military ideology that demanded clockwise staircases in the cause of fighting efficiency or advantage".

Developments in manufacturing and design have also led to the introduction of kit form helical stairs. Modular, standardized steps and handrails can be bolted together to form a complete unit. These stairs can be made out of steel, timber, concrete, or a combination of materials.
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