The Friends of Dag Hammarskjold Plaza and Rooftop Films present a free outdoor screening of "Guess Who's Coming to Dinner," starring Katharine Hepburn, Spencer Tracy and Sidney Poitier. Before the film, guests can take a tour of the Katharine Hepburn garden within Dag Hammarskjold Plaza at 7:30 p.m. At 8 p.m., actress Katharine Houghton, Hepburn's niece, will particiate in a Q&A. The film is scheduled to begin at 8:30 p.m.