Basement or cellar shows you what is usually unconscious or below your normal daily awareness. Also it may still have associations to do with ‘below stairs’ referring to what is beneath one or a lower class.
In the cellar or basement you is near to the earth, the primal forces of your nature, what moves beneath the ‘street level’ of your personality. The basement can link you with what your present personality has been built upon, what you have inherited from your past or family and culture. If there are no walls to the cellar, or tunnels leading from it, it shows an openness or connection with influences beyond your own personality.
What does my dream show me is happening in the deeper levels of my mind?
Is it clear what the atmosphere or condition of the basement is, and what this says about my inner life?
Am I scared of who I am deep down in me?