architecture construction corkscrew stairs flight of winding stairs grate grated helical metal shape shapes spiral spiral staircase stair staircase stairs wentletrap winding stairs emergency exit escape route escape way fire exit security spiral stair ironwork lighthouse spiral stairs spiral step stairway step steps abstract ancient bottom building circle circular climbing stairs design dynamic form high house hypnosis infinity inside interior landmark monument old pattern round stairway to heaven swirl swirl background tall top tower UP Asia blue color colored colorful colors colour coloured colourful colours escapes fire escape fishmonk green patterned patterns primary rainbow rainbows red repeat repeating same Singapore spirals stripe striped stripes stripy yellow