About twenty years ago, I was training to be a lawyer in Birmingham, UK. The offices were two old houses knocked together, so had uneven floors etc. It was a happy office and I enjoyed working there.
I hadn't had any supernatural experiences there, even though I have had many such experiences over the years.
That was until, one Friday evening, I was working late and alone, to finish something that was needed for the following Monday. Obviously I was tired and the old building was creaking a bit. That wasn't a problem, because it always felt homely and I knew the noises were down to the (rather shoddy) way the two buildings had been integrated and the fact that it was settling down for the night.
At about 9pm, I was alerted to the sound of a door upstairs slowly and deliberately shutting. I jumped out of my skin, because I knew I was the only one in the building. I reasoned with myself that someone had just forgotten to close a window and an unevenly hung door had probably just caught a breeze. The trouble was that it was not windy outside and the doors were very old and very heavy. You had to push them to move them. In any case, we were all under strict instructions to close the office doors when we went home to stop the spread of fire, so there should have not been any doors open.
I sat as still as a mouse, straining to hear anything else, like a burglar's footsteps. There were none, but suddenly my scalp started to feel as though it was trying to turn itself inside out with fright and my blood actually ran cold. Instinctively, I thought "Don't radiate fear, it will only pick up on it and come for you". I have no idea why that particular thought came into my head but I was absolutely terrified and I don't scare easily.
Slowly and cautiously, I switched off the computer, picked up my bag and coat and walked as calmly and smoothly as I could to the front door. I could still feel this "thing" waiting and listening upstairs. I managed to switch the burglar alarm on and closed the front door. Then I raced to Snowhill station and went home, still shaking. On Monday, I came in early to finish the work, but didn't dare ask whether anybody else had ever experienced anything like this.
This probably isn't as frightening a story as some, and you could put it down to being alone in an old building late at night. However, in spite of having many supernatural experiences over the years, this remains the most frightening I have ever had.