"So a couple of years ago I was living in an old apartment building in Seattle with a couple other people. It was a really old building that was sandwiched right up next to the neighboring buildings. It was one of those situations where they're so close there isn't even a sliver of an alley; the sides were basically flush with one another.
It was a medium sized two story place with a half second floor where the bedrooms were and a wide wooden plank staircase that led from the bedroom floor to a shared rec area/kitchen at the back of the apartment.
The whole building was brick and wood and so was drafty and creaky, but nothing that I wouldn't by default attribute to just "old building noises". But one night I woke up at like 2 o'clock in the morning with a pretty bad stomach ache, and after trying and failing to fall back to sleep decided to head downstairs to try to find some Alka Seltzer.
About a third of the way down the stairs, I not only heard, but FELT something coming slowly down the stairs behind me. I was pretty groggy, and assuming it was just one of my roommates turned around to see. But there was no one there. The steps however kept coming. Muffled creaky steps and I could SEE the planks of the staircase bowing slightly with each step, coming slowly towards me.
Now I'm one of the most staunchly anti-superstition, pro logic, pro science and reason person I know. The kind of person who, if I saw a literal ghost that I could examine and interact with, wouldn't think "ghost" I would think "extra-dimensional alien" or maybe just "I'm having hallucinations", and maybe it was because I was also half asleep, but I just stood stone still fucking frozen with a deep panicky dread that completely bypassed the reasonable part of my brain.
The steps continued until it reached the step I was on and I FELT the stair bow slightly underneath me and reverberate with the phantom step. The steps continued to the bottom of the stairs before stopping without a trace. Now I honestly couldn't tell you what I was thinking at that moment but I was wide awake and under no illusion that I had just imagined that.
I didn't wake up any of my friends, but told them about it in the morning. Now they knew me well enough to know that I wouldn't put any stock in something I had dream or imagined or anything like that. If I was taking it seriously and talking about it the way I was, it either really happened, or there was something seriously wrong with me mentally. In either case it wasn't a matter to be dealt with flippantly. So they agreed to stay up with me and see if it happened again.
And sure enough, it did. At the exact same time and in the exact same way. The steps started on the first stair, there was sound and movement of the step, and they passed slowly down the stair case, disappearing after the last step.
After a few moments of being legitimately spooked, we immediately started trying to figure out what the hell might be causing it. Weird temperature fluctuations, some kind of elaborate prank? We stayed up the next two nights, and on the second night it stopped."
Much as Tombombodil provided the story, he also provided an explanation for what occurred:
"So what was happening is that at some point, the section of the building we were in shared a stairwell with the building next door, the wooden staircase in that stairwell got retrofitting into the stairs between the floors of our apartment. But the wooden planks of the stairs were still the same planks that spanned across to the other building even though they had partitioned the space off with walls etc.
So some guy who worked night shifts was getting up, and coming down the stairs to go to work, and was stepping on the other half of the same planks that made up our stair case; thus the sound, vibrations, and movement."
Thanks, Tombombodil, I very much enjoyed this one.