The hidden Basement below the basement

"I went into my basement to grab something from storage, though I don't remember what. The lights were already on, which was weird because I usually keep them off. The basement looked bigger than normal, like someone had knocked down a wall and added another room. I walked past the usual boxes and old furniture, then noticed a set of stairs going down farther than they should. I don't know why I went down them. At the bottom there was another basement, almost identical, except the boxes had different labels and there was a couch facing the wall. I heard someone moving around upstairs, so I called out, but my voice echoed like the space was huge. Then I noticed the stairs behind me were gone—just a smooth concrete wall where they used to be. I woke up before I could find another way out, and I kept checking the basement door for a while after."