“Vital cities have marvelous innate abilities for understanding, communicating, contriving, and inventing what is required to combat their difficulties… Lively, diverse, intense cities contain the seeds of their own regeneration, with energy enough to carry over for problems and needs outside themselves.” — Jane Jacobs Whenever I take a stroll on New York’s Highline, I think about the creativity, ingenuity, money, politics and gumption it took to bring it to life. What some might have seen as an old, decrepit railroad trestle, others had the vision to retrofit it into a lush, elevated park that has added immeasurable pleasure to Manhattan dwellers and visitors alike. This is sustainability in action: an urban infrastructure turned urban green machine, improving air quality, affording new views of the city and providing a happy respite from the hustle. Why is this so important? The environment that surrounds you is the quality of your life. It’s as simple — and as incredibly hard — as that. During its upcoming summit on September 25, the United Nations is adding “Sustainable Cities …