This week we nerd out on kohlrabi (available November - April). To appreciate kohlrabi, you need to understand another engineering marvel: modern skyscrapers. Steel is at the heart of how we are conquering heights, densifying cities, and optimizing hard-to-find space. Up until the late 19th century, buildings had self-imposed height restrictions: at a certain point, the additional material on a taller building would be too heavy and the building would collapse.