Today I had a dream in which there was a room that isn't there. I don't remember how could it be accessed, but somehow it could. It materialized within the walls of my house, however from the outside my house looks pretty much normal. The inside of that room looked like an old attic, however it was dusty, covered in cobwebs and made from wood, where the actual attic is from grey bricks, blocks, only the roof is wooden. What's more, the actual attic did exist, untouched. The position of this room would be around the door to the bathroom and to the attic, since the entrances to both are next to each other). Inside that room there were also sun rays, which implied some sort of light source from the western side of the house (the house is aligned in such way that actual east is at one corner, west is at another corner).
Another thing is that this room lead to a balcony from the northern side of the house. My house has no windows to the north except for the one window in the bathroom and in the boiler room. Also the balcony which actually exists is on the southern side of the house.
I wouldn't care if I had this dream just once, but it happened again today and from the looks of it it was the exact same design.
Picture partially related, as I live in a kind of similar house, though in the countryside if that matters. My house has no other extensions apart from the balcony, as the one in this picture has separate garage and entrance, mine is just a cube that's 10x10x10.
I don't remember when I had this dream for the first time, but around 2 months ago if not less.
Additional detail I feel like could be worth including - when I was around 5-7 I imagined that there was some sort of passage through the empty wall that's sandwiched between the attic and bathroom doors.
I'm also including a rough sketch of this corridor. It's an empty wall that just has a cross hanged on it. It was hanged in December last year, as it was previously above the entrance to my room, however I placed a clock there instead.