architecture spiral spiral staircase staircase stairs step construction corkscrew stairs flight of winding stairs grate grated helical metal shape shapes stair wentletrap winding stairs emergency exit escape route escape way fire exit security spiral stair metalwork monotone old past rusty spriral staircase circular corner dark diffused-light gray grey handrail inside interior intricate light limited patterned patterns shadowy silhouette spiral-staircase spiraling spiralling steps structure sturdy turning turns window wrought-iron abstract ancient bottom building circle climbing stairs design dynamic form high house hypnosis infinity landmark monument pattern round stairway stairway to heaven swirl swirl background tall top tower UP angled angles architectural-elements ceiling greyscale lighting monochrome reflections shiny upstairs flooring polished sepia