Over the past four years, Marvel Studios have slowly been putting together the pieces to form The Avengers, a film version of the comic series that brings some of the studio's most powerful heroes together. The ambition of the project cannot be overstated: over five films, the studio have constructed an approximation of their comic universe that remained faithful to its origins without ever producing films that were only aimed at the converted, even if sometimes, as in the case of The Incredible Hulk, only the converted showed up. Considering the risk involved - the very real possibility that, had any of the films faltered badly in the early going, the whole thing could have fallen apart - the build-up to The Avengers alone is something quite remarkable, maybe unprecedented.