Los Angeles, Dec 19 : Filmmaker Christopher Nolan explains why the Cillian Murphy-starrer 'Oppenheimer' is his most successful film to date. He also talked about the movie business. The filmmaker struck box office gold with 'Oppenheimer' this year. Nolan is now looking back at the year and giving his take on the cinema landscape as of now. 'I've just made a three-hour film about Robert Oppenheimer, which is R-rated and half in black-and-white ' and it made a billion dollars. Of course I think films are doing great,' Nola said in an interview with Empire. 'The crazy thing is that it's literally the most successful film I've ever made.' He continued: 'I've been doing this for 20 years and in the United Kingdom, it's my highest-grossing film. So, I feel great about the state of the movie business based on my own experience. But also based on seeing other movies break out, seeing audiences come back.' Nolan is frequently asked to give his opinion on the Hollywood industry. Having directed superhero movies in the past with The Dark Knight trilogy, he is often queried about the reliance on this genre in more recent years versus other types of films. Nolan feels the industry needs a good balance of all types of movies to keep it moving. /IANS