Abstract: A system for reversibly providing a wall, comprising: a first panel comprising first track followers on each of opposite side edges of the first panel; a first pair of tracks adapted to receive the first track followers and that are generally vertical on opposite sides of a space, each comprising: a top at a point overhead, and a lower point part-way to the floor of the space; a second panel comprising: upper second track followers on sides of the second panel near a top edge of the second panel, and lower second track followers on sides of the second panel near a bottom edge of the second panel; wherein, as the first panel is lowered, the first track followers ride in one of the first pair of tracks until at least one first track follower reaches the bottom of the one of the first pair of tracks, thus allowing the first panel, when lowered, to form a first portion of the wall; a second panel comprising: upper second track followers on each of opposite side edges of the first panel proximate to a top edge of