Celebrate Earth Day by learning about sustainability and helping the environment at the annual outdoor festival held in Union Square, featuring over 70 exhibitors including environmental non-profits, local green businesses, kid’s activities, and live performances. To see environmentally-conscious locations first hand, participate in the 5K Earth Day tour on April 20th, which takes participants to sites across the city such as the Lowline (the world’s first underground park), a rooftop farm, a natural food cooking school, and other “green” places.