An announcement was made in July 2006 that Christian Bale would continue in the role of Batman in the sequel to Batman Begins. Warner Brothers also announced that Heath Ledger would play the role of The Joker, with actors actors Paul Bettany,Lachy Hulme, Adrien Brody and Robin Williams all previously rumored. At this same time Warner Bros. officially initiated the production of The Dark Knight, using David S. Goyer’s treatment, co-written by Nolan.
The role of Harvey Dent, District Attorney of Gotham City and otherwise known as Two-Face, was cast in February 2007, to be played by Aaron Eckhart. Around this time, despite previous mentions that Katie Holmes would return as Rachel Dawes, it was made known that Holmes would not be involved in the sequel, due mainly to scheduling conflicts. In March this year Maggie Gyllenhaal became the replacement. Anthony Michael Hall, of 1980s Breakfast Club fame, also has an unnamed role in the film.
Nolan’s interpretation of the Batman franchise shall continue to be very different to that of its redecessors. The Joker character is based primarily on his first two appearances in the Batman comics, as well as Alan Moore’s one-shot comic book Batman: The Killing Joke. Principle photography began in April 2007, pushed back from March, beginning in Chicago between April 18th and 24th — shooting scenes for the Joker’s prologue, as of June 9th they have returned to continue filming there until early September. Tentative filming locations also include London, Liverpool, Los Angeles, Baltimore, and Hong Kong.
Hans Zimmer and James Newton Howard have confirmed that they shall provide The Dark Knight’s score.