The premiere of the new and most expensive movie in the world so far by Titanic director James Cameron was held in London which was attended by the whole cast of the movie besides Cameron himself. A large number of people attended the screening of 3-D movie Avatar held at Leicester Square, London. Sci-fi Avatar is a movie about a clash between aliens and human beings inhabiting an imagined planet. The movie cost $500million, in which 3-D fusion cameras were employed during the making. The movie will hit the screens on December 15. Earlier, Titanic was considered as the most expensive flick made with a hefty amount of $200m.