When Stapleton International Airport was retired, most of its concrete runways were crushed and reused (as an aggregate) in constructing nearby warehouses. But the more incredible runway-return-to-nature vision lies along Westerly Creek Trail, hidden beneath the MLK Boulevard bridge. Here, large concrete chunks were used like stones to line the hike and bike trails and retain the soil of low rolling slopes around the bridge. The concrete slabs look amazingly "natural" — almost like stone rockfalls — in a park that was landscaped with native plants. The beauty of the Westerly Creek Trail makes it a local favorite and proves that if we unbuild it, they will still come.