"What we're doing here is completely unprecedented," says director Joss Whedon, in this exclusive look at "The Avengers."

Fans have been eagerly anticipating Marvel's upcoming superhero epic -- which brings together Iron Man, Captain America, Thor, the Hulk, Black Widow, and Hawkeye for the first time ever on screen -- since the Avengers Initiative was teased by Samuel L. Jackson (Nick Fury) and Robert Downey Jr. (Iron Man) at the end of the first "Iron Man" back in 2008.

In this behind-the-scenes featurette, audiences get a look at the work that went into shooting this massive project. The clip also features interviews with the cast (including Scarlett Johansson, RDJ and Chris Evans) and Marvel Studios President, Kevin Feige, who discusses one of the movie's main plot points: The Cosmic Cube.

You can check out the full video above.

"The Avengers" hits theaters nationwide on May 4.

PHOTOS

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• Robert Downey Jr. (Iron Man)

• Tom Hiddleston (Loki)

• Jeremy Renner (Hawkeye), Scarlett Johansson (Black Widow) and Captain America (Chris Evans)

• Jeremy Renner (Hawkeye)

• Captain America (Chris Evans)

• Chris Evans (Captain America)

• Tom Hiddleston (Loki) and Chris Hemsworth (Thor)

• Captain America (Chris Evans) and Clark Gregg (Agent Coulson)