A retaining wall serves a structure that holds soil on one side and is free standing on the other. They help to accommodate changes in grade in a landscape with uneven topography. Retaining walls allow cuts to a slope to provide more usable space or extend the area. Engineer retaining walls can are a key to retain massive areas, like a commercial parking lot, structures and buildings, create a level area for sports lawn or driveway too, small walls can also serve as sitting walls if properly planned.