This retaining wall’s 7.5 tons of concrete – or “urbanite”, as recycled concrete is sometimes called – is 100% reclaimed from local sidewalks. In 2009, the City of Ann Arbor began requiring residents to replace damaged sidewalks on their properties, which led to an abundance of this material at the local concrete yard. Since sidewalk concrete is generally poured to a uniform thickness, it makes good material for stacking if you have enough of it. All except the top course of these concrete pieces were