A wall is not something that would usually come to mind if someone asked you to think of a spiritual symbol yet, under some circumstances, it is.  Generally, a wall represents the division between the material world and the spiritual, between the heavens and the cosmos.  The "Great Wall" protects the cosmos (spiritual dimensions) from the darkness.  A wall can represent protection or limitation.  A wall can represent a barrier that we need to get over.  In Hinduism, a wall represents stability.  
    A wall can also represent growth.  Shortly after I joined the International Community of Christ, I had a dream in which I was helping several members of the community building a brick wall.  This was clearly a case where the wall represented growth, or building something together.  This dream was one thing that helped to convince me that I belonged in the community.
     Paintings or writing on a wall are said to represent absolute or ultimate truths.  
    The story of the Walls of Jericho tumbling down may be about an actual, historical, physical event but, on another level, it is a tale about breaking down the barriers between the material and the spiritual.