After four years, five films, and countless castings, The Avengers have finally assembled. In less than 24 hours, anxious fans will see Iron Man, Thor, Captain America, Hulk, Black Widow and Hawkeye fight side-by-side on the big screen. The Avengers Hollywood premiere took place last month, and immediately after, the cast participated in a press conference where they dished on their characters and each other.

Check out some highlights below…

It all began in 2007, when Robert Downey, Jr. was cast as genius, billionaire, playboy philanthropist Tony Stark in Iron Man. The film planted a seed that would grow and spread into the next Marvel films, leading to this cinematic event.

Robert Downey Jr.: Going back to 2007 when I was cast in Iron Man and Kevin Feige over there said, you know, this is all going to lead to where we’re going to have all of these franchises come together. And, we’re gonna do something unprecedented in entertainment. We’re gonna make this Avengers movie. And I just remember, I would get nervous about it and excited about it and doubtful of it.

Initially, director Joss Whedon shared Downey’s nervousness. He knew The Avengers would be a huge undertaking, and wanted audiences to be satisfied with the finished product.

Joss Whedon: I think the exciting thing kind of speaks for itself. That bunch of characters,that bunch of actors playing them,that much money. It was kind of a no brainer. The hardest part is and always will be structure. How do you put that together?  How do you make everybody shine? How do you let the audience’s identification drift from person to person without making them feel like they’re not involved. It’s a very complex structure. It’s not necessarily particularly ornate or original, but it had to be right. It had to be earned from moment-to-moment, and that’s exhausting. That was still going on in the editing room after we’d shot.

No one knows about trying to identify more than Mark Ruffalo. The actor had the tough task of replacing Edward Norton, who played Bruce Banner in 2008′s The Incredible Hulk. After being cast, Ruffalo quickly learned how harsh and critical the fanboy community can be.

Mark Ruffalo: It was terrifying. I knew what my responsibility was — or I felt it just by making the mistake of going online and reading some of the fanboy responses to the announcement that I was playing the next version of Bruce Banner. That was a mistake. I will never do that again. I’ve never had a role be more scrutinized and criticized even before I shot a single frame. Coming onto the set with all of these guys was pretty daunting. I knew that I had big shoes to fill, so to speak.

Ruffalo wasn’t alone in feeling out of his element. Chris Evans, who plays Captain America, also had to switch it up. The majority of the film’s jokes are handed off to his counterparts, while he delivers earnest dialogue. As someone who’s spent the majority of his career playing smartasses (like Johnny Storm in Fantastic Four), Cap was a welcomed change.

Chris Evans: That’s his role. It’s necessary, and that’s kind of why I like it ’cause I am used to kind of leaning on cracking jokes and being a wise ass. It’s nice to kind of play it straight a little bit. You know, that’s — I think even in this film more than the first Captain America, he, Steve Rogers has some issues, some conflict, some trouble given the fact that he is, a man out of his time. But given who he is as a man, his nature, he puts that second. He puts the mission first, and he’s just selfless.

Chris Hemsworth‘s Thor couldn’t be more different from Captain America. In his first film, he was forced to eat a huge slice of humble pie because of his arrogance. And even though he’s learned the error of his ways, Hemsworth believes Thor’s stubbornness is one of his best qualities.

Chris Hemsworth: I like the sort of visceral, gut instinct that Thor has. I always thought the childlike quality in the sense that if he believes something or, he wants to do something, he does it and says it. You know how kids own their environment and there’s no opinions that they really care about. I think Thor is — it’s there. It’s surrounded by bravado and strength and all that, but end of the day he’s pretty true to who he is and what he wants to do.

Thor will have plenty of time to show off his strength and bravado when he (once again) goes head-to-head with his brother Loki. As the film’s villain, Tom Hiddleston has the honor of battling not one but six of Earth’s Mightiest Heroes. It’s a fact the actor has a hard time wrapping his head around.

Tom Hiddleston: It’s such a great character. It’s like playing an iconic Shakespearean character or something.  It’s just a privilege to be asked to do it. With a character like Loki, he’s got such a level of complexity and so many layers to him. When I read it, I couldn’t believe my luck. The film was called The Avengers and yet Loki was almost on every page. I just was so excited about it, so I was, there was no trace of fear, just a huge amount of fun.

Two-time Oscar-nominee Jeremy Renner had an interesting way of preparing for his role as Hawkeye. As the team’s master archer, he does things with a bow and arrow Katniss Everdeen (The Hunger Games) and Legolos (Lord of the Rings) could only dream of.

Jeremy Renner: I stretched a lot, and I prepared by stretching. I did take some archery, but I realized very quickly that I couldn’t really use it in the film. It ended up being superhero type archery. It is nice to know the technique behind it but then, you know, shooting behind my back and over my shoulder and using fake arrows and blah, blah, blah, blah, blah. I gave it a go and shot a few bales of hay and missed a few. And yeah, you get injured, banged around every day when it’s hand-to-hand stuff.

Cobie Smulders, who’s best known for starring on CBS’ How I Met Your Mother, opened up about making the transition from TV to film.

Cobie Smulders: I made it a point to do a lot of training to prepare myself for this role with weapons and to get myself mainly comfortable using them. That was the thing that I tried to do the most. In terms of schedule, it’s very different. I’m very blessed at my job at How I Met Your Mother. We have a very nice schedule,and this too was,very good. But we had a lot of stunts to do and a lot of fun things to explode, so it’s very different.

As the director of S.H.I.E.L.D. and foreman of The Avengers, Samuel L. Jackson revealed what he really loves about his character. And why Fury is dead-set on making this team work.

Samuel L. Jackson: I just like the fact that Nick Fury believes that these unique individuals deserve the love and admiration of the world. We pretty much owe everything to [The Avengers] because there are things out there greater than us.

The Avengers opens nationwide May 4.