Retaining walls have a wide variety of uses around the yard, all of which involve keeping earth from spilling off a steep slope. They’re indispensable in the creation of sunken patios, walkout basements, in-ground pools, and any other hardscape with an abrupt separation of ground elevation. You’ll also find retaining walls in parks and public gardens, where they act as retainers for plants, statues, and decorative landscaping elements.