5121: This floor consists of a single, completely empty room, which has a single balcony. The balcony platform allows you to look far. The sky's color is blue-green, which gives a rather strange feeling. More familiar white clouds roll beneath you, but the surface, if there is even any, is invisible. Strangely, the air is breathable, despite what your common sense says.
You wondered if this building's floors are even actually connected physically. Observation from this room suggests otherwise, with the entire building above you appearing to be a tall, slender pillar with no visible feature. No windows, no balconies, no variation in size, not even difference in colors. It's like you're in some sort of limbo, but after everything you've experienced, you don't really mind this floor's peculiarity.
Just as you turned back towards the staircase, you caught a glimpse of a person running down the stairway. You swore you saw your own face in that split second the figure rushed past. Nevertheless, you decided to ignore them and continue upwards.