Lost in a big house

It often starts as a visit to a somewhat familiar house with several rooms, and sometimes several entrances. Sometimes it becomes a building with multiple condo units of varying floor plans. In the building a stairway leads to an upper floor where there is a long dark hallway with doors, supposedly rooms on either side of the hallway. One room has its door opened and across the room  opposite the door is another stairway, a circular one,  The stairway  goes up several more flights and ends at a closed door. I knock on the door and it creaks open. There is a shadowy figure deep inside the dimly lit room. I become suddenly frightened, believing this to be the horrid, evil witch of my nightmares. I bolt from the room to descend the stairway and get out of that place, but suddenly chunks of the stairway disappear and I have to leap from landing to landing.  I remember nothing after the leaping!