For the 20th year in a row, the "virtual greenmarket" offers outdoor wellness activities, music and dance performances, and quirky workshops like creative movement (11am) and improv theater (4:30pm). Line up for the "As Long as It Rolls" parade (11:30am), where kids deck out their scooters, strollers and bikes and vie for prize-winning titles like Best Dressed Easy Rider. Then, join in a flash mob to a mashup of Stravinsky's "Rite of Spring" and the Harlem Shake (12:45pm). Little ones even get their own special corner with clowns and a puppet show (2–4pm), and the whole shabang wraps up with an open dance party in the street (8:30pm)—by that time, though, the kids'll likely be wiped out. All ages.