It's easy to stand in awe of a city's impressive skyline, marveling at its buildings reaching for the clouds and its vast network of roadways and train lines crisscrossing in every direction. It can often seem like everything in a city is man-made, all concrete, steel, and glass. But even the asphalt jungle is not all asphalt--a sidewalk's cracks are filled with nature, if we know where and how to look. To aid us in this quest is Nature All Around...