corkscrew stair

spiral stair, caracole, circular stair, cockle stair, corkscrew stair, spiral staircase

spiral stair
A flight of stairs, circular in plan, whose treads wind around a central newel. Also called a helical stair, solid newel stair.
References in periodicals archive ?
You can walk inside, but you can't walk up the corkscrew stairs to the top or see the lens.