Double sided poster advertising events in Central Park, New York City, on Sunday, October 23, [1966]. During the one-day festival Belvedere Castle was converted into a fun house, with an enormous balloon sculpture that floated in the Belvedere Lake, and the castle building took place under the stands of the Delacorte Theatre. There were slides, music, public dancing and an exhibition of paintings created by children and adults from all over the city. Recto lists sponsors and characters for the day. Verso lists events such as "castle building," "sound making," "costume making." The festival was conceived by Phyllis Yampolsky, a proponent of public art