In just a couple of weeks, directors Anthony and Joe Russo are bringing together more than a decade's worth of world building for the main event, otherwise known as Avengers Endgame. Disney has yet to confirm the running time (which has been rumored to be three hours), but in an in-depth interview with Joe Russo (fromBox Office Pro), the co-director shed some light on why Endgame is so special.

“It’s been a really unique experiment. It’s been 10 years of multifaceted, serialized storytelling—multiple franchises with highly successful characters in every franchise. The audience has an emotional investment across all of the franchises in a way that I don’t think has ever been done before in the film business. Certainly, there have been singular franchises like Harry Potter, The Lord of the Rings, or Star Wars as you go down the list, but I don’t know that anyone’s ever done multiple franchises like this that have all built toward a finale like Endgame,”

When asked about how long the movie was, Joe revealed that the film hasn't changed drastically since the first cut, and "wrapping up 10 years of storytelling" in a compact running time was challenging. 

“We’re still looking at a similar time [approximately three hours]. This one’s been very specific in its run time. It really hasn’t changed since we executed the first cut of the film. Even though we’ve shot a lot of footage between now and then, we’ve swapped things out and the water keeps rising to the same level because the story’s so dense. We have so many characters that we’re working with again that require that kind of run time. My brother and I are really committed to emotional stakes, and emotion requires story real estate. When you have a sprawling plot with a lot of characters and emotional stakes, it requires time to breathe emotionally. On the scale, you’re just going to wind up at a certain run time. We’ve been really hard on the film. We don’t like excessive run times; it’s just very difficult wrapping up 10 years of storytelling.”

At this stage, I'm not sure fans are going to be too bothered by a three-hour grand finale. After all, Endgame will be a very literal endgame for many of the original MCU heroes, and we need a proper send off.

Avengers Endgame is released in the UK on April 25, and lands in the US on April 26.