Movies based on historical events will take front and center at this year's Venice Film Festival -- and the stars that appear in them will be on hand for the screenings, festival officials indicated today (Thursday). Nicolas Cage will attend the premiere of Oliver Stone's World Trade Center. Sharon Stone will appear for the screening of Bobby, a film about the hours leading up to the assassination of Robert Kennedy in 1968. Scarlett Johansson will fly in for the festival's opening film, Brian De Palma's The Black Dahlia, about the 1947 murder of Elizabeth Short. And Helen Mirren is due to arrive in Venice for the screening of The Queen, in which she portrays Queen Elizabeth II during the days following the death of Princess Diana.