In 1975 we, Mum, Dad, and three of us girls, moved into the ground floor and basement apartment of a tenament building in Glasgow,Scotland. From the start, we girls (Mum doesn't have a sensitive bone in her body) found it difficult to enter into the front, main bedroom. This room appeared to be always cold, and nothing seemed to heat it properly. Our German Shepard, Candy, wouldn't enter the room unless we dragged her in there.
When we walked through the entrance foyer on the ground floor level, sometimes we'd feel as though we walked through a pocket of cold, still air, and on on those occasions Candy would appear unsettled, pacing the foyer, sniffing the air. This was all that we felt for about two months, then things started to pick up the pace.
I remember the first night I got really, really, scared, as opposed to feeling uneasy. We were all sitting in the lounge, with the door shut to keep the heat in, watching TV, when Candy leapt up, from a deep sleep, growling, hackles fully raised, and stalked over to the door. Our first collective thought was that we had an intruder in the house, so Dad opened the door for Candy. She took a flying leap into the foyer, still growling and carrying on, and proceeded to watch something, which we couldn't see, move from the front bedroom across the foyer, and around the corner to the area containing the kitchen, bathroom, and stairs leading down to the basement area. Dad tried to step in front of Candy, to see if anyone was hiding around the corner, but she turned on him, forcing him, and the rest of us, back into the lounge. One doesn't argue with a 45 kg dog behaving like that. I must add that Candy was named because of her sweet nature, and had never shown that she was capable of being so enraged before.
After about ten minutes Candy settled down, and Dad went through the house checking that things were as they should be. They were, but that didn't stop Candy repeating the performance on a regular basis - terrifying if one was in the house alone.
No one in the family saw or heard anything at all, just the feelings we experienced, which were enough, thank you. Right up until the day we left the house our younger sister, then aged 14, could not be convinced to walk through the foyer alone, and I must admit that whenever I'd move through the foyer I'd ensure that Candy was close at hand.
My elder sister used to feel a presence passing her on the steps leading to the basement, as did my younger sister, my I never experienced that at all. Dad thought once that he felt a "shove" to his back while standing, talking at the top of the stairs, but he, to this day, doesn't like talking about the house.