When I was seventeen, many years ago, I worked in a building that was part of the old Thames watergate, near the embankment. When the cleaner left unexpectedly, a couple of us young ones decided to do it for a few weeks after work to earn some extra holiday money. We would be given a key when the last person left and lock up, posting the key back through the letterbox when we'd finished.
It was a very old building with a stairwell encased in wood and frosted glass, my friend was on the ground floor and I was in the semi basement passageway, I heard her coming down the stairs and saw her shadow go passed the glass. I opened the door and called her to see what she was doing and she came out of the office behind me.
They persuaded us to finish the week and we decided we would but we would stay together at all times.
The next night we were in the basement office and there was a terrific crash outside the door, we ran out and there were reams of paper strewn the whole length of the corridor. It had all been stacked neatly against the wall earlier. My hair is standing on end just remembering it.
Needless to say our cleaning days were over, and we were teased by everyone. The teasing stopped when a few weeks later one of the girls decided to set up a ouija board in our lunch hour. Everyone was giggling until the glass flew off the table and smashed.
The strange thing is I don't believe in anything woo at all, I don't believe in spirits or ghosts, I think there's always a logical answer, even if we don't know what that is.