I used to live in a really old building with 2 flats in it in Shrewsbury with an ex-gf. Apparently it was a pub about 300 years ago. Somone lived in the flat below us and you could hear them walk up the stairs and unlock their door, open it, close it etc. Sound carried really well through the stair case. Occasionally we'd hear the footsteps but no door stuff, so we'd joke about the ghost.
After we broke up whilst we were sorting our shit out I started to sleep in the spare bedroom.
She went out on a night out with work one time while i was in. I went to bed and shut the bedroom door, and I heard at around midnight some footsteps coming up the stairs, and thought 'it's the ghost' but they carried on up the 2nd flight. I'd left the door unlocked so she could get in quieter and not fuss with keys etc. I heard out front door open, then the bathroom door open and close. After a while nobody had come out, so I assumed she was pissed and maybe fell asleep on the toilet or something. I got out of bed, knocked on, nothing. Opened the door, nobody there.
She came home about an hour later.
For the record i don't believe in ghosts or anything like that but can't really explain it.