Nature's uneven terrain has its charm, until you try to play croquet on a hilly lawn or enjoy a candlelit dinner on an off-kilter patio. Install a retaining wall as a backstop, though, and you can literally carve out functional outdoor spaces where once there were only precarious slopes.
More than problem-solvers, retaining walls also have a sculptural quality that adds definition to the landscape, and they can be made from various materials to evoke different styles. Stacked timbers or mortared stone, for instance, can impart a rustic look, while poured concrete is sleekly modern.