During his three terms as mayor of Curitiba, Brazil in the 1970s and ‘80s, architect and urbanist Jaime Lerner transformed his city into a global model of the sustainable and livable community. From the pioneering Bus Rapid Transit system to parks designed to catch runoff and reduce flooding, and the creation of pedestrian-only zones, Lerner has been the driving force behind a host of innovative urban projects. In more than forty years of work in cities around the globe, Lerner has found that changes to a community don’t need to be large-scale and expensive to have a transformative impact—in fact, one block, park, or a single person can have an outsized effect on life in the surrounding city.