When I was 13 years old, my parents rented a house in St. Louis that turned out to be haunted. We only spent six months in the house, six months that were so disturbing and upsetting that we still (20 years later) marvel that it took us so long to leave.
The house was a very pleasant 2nd and 3rd floor flat. The 2nd floor had the main living areas of the house and two bedrooms, while the spacious upstairs had two large bedrooms and a small kitchen. Since the haunting originated in that upper floor, we often thought that perhaps it had been an in-law apartment for someone who did not wish to leave.
We began to sense that something was wrong the very day we moved in. Everyone experienced the following sensation more than once. While distracted, reading, watching TV, or eating someone would without warning be overcome by the sensation of being watched, usually from behind and above. It would make the hair rise on the back of your neck, and be followed by an irrational wave of fear. Not simple apprehension: something numbingly cold that seemed to petrify you, robbing you of the ability to speak or move, while at the same time making your heart race like crazy. This sensation was unique to that place: it was in no way the ordinary response that once calls 'fear.'
In retrospect, I believe that sensation was caused by being physically attacked by the entity in that house. True I have no evidence for this: but I can contrast it with a related sensation. Sometimes, the feeling of being watched came from another part of the room, and it remained there, apart from the victim. On these occasions that intense cold fear, accompanied by adrenaline-rushing alarm responses was just not there. As a result, I think the experience was caused by direct contact with the ghost.
My bedroom was on the third floor (very briefly) ... as within two weeks of moving in, we realized the 3d floor was completely uninhabitable. Not only were the sensations I mentioned above so strong and so common that it was impossible to sleep there, odd noises and lights occurred at different times of day with great frequency. The culminating event (at 2 weeks) was that it attacked me while I was asleep.
Sometimes the noises sounded as if the very walls were being torn out. At other times there it almost sounded as if a party was going on, with the sound of lots of voices, some of them laughing, others weeping, and most just babbling. At other times, a solitary set of footsteps would slowly descend (in the middle of the night) to the 2nd floor. The walker would move the length of the hallway to the kitchen, and then would walk around in circles for about an hour. Long, slow steps, as if dragging a slipper across the floor. When this occurred, often, overhead lights or lamps would turn themselves on in an adjacent room around the time the pacing stopped.
As silly as this sounds, I'm going to mention it because many people who would otherwise not have known about the house learned about it in an unusual way. Sometimes "it" would enter the phone line. We had numerous conversations in which the people we were talking to would say that they felt someone else had come onto the line. They would insist that someone else had picked up an extension... and in most cases, they would become so uncomfortable with the sensation that they were under some kind of surreptitious surveillance that they would have to quit the line.
Other odd events occurred too, but I'm omitting them just for brevity.
We probably delayed leaving as long as we did because we spent all our waking hours trying to avoid panic reactions to what was going on, while trying to come to grips with the reality that we were powerless to control it.
Whenever I visit St. Louis I always drive by that house so that I can stare up at the windows of the 2nd and 3rd floor. Only on 1 occasion have I not had the sense that "it" was still there. I can't explain why I go there, because I can say emphatically that I would never enter that building again under any circumstances. Whatever is there, it feels very mean and very disturbed, if not evil.
I'm going to include the address in hopes that someone with a serious research interest might look into it: 3314 Magnolia Avenue, St. Louis, USA.