Actor Zach Galifianakis had to conquer his fear of heights during the making of The Hangover Part Iii while shooting a scene atop a 60-foot (80-metre) building.

In the final film of the popular trilogy, the funnyman is featured on the roof of Caesars Palace trying to save his co-star Bradley Cooper, who is dangling high above the ground by a bed sheet.

Set designers recreated the famous Las Vegas hotel and casino in a sound stage in order to shoot the clip, and the Oscar nominee admits he was impressed by the 43 year old's bravery.

During an appearance on U.S. breakfast show Today on Monday (13May13), Cooper said, "We were really high, actually. They re-built the facade of Caesars Palace inside the largest studio at Warner Brothers. I think it was about 60 (feet tall), there was about seven or eight floors.

"Zach was a real trooper because he's very scared of heights. And he kept saying, 'Well, what if there's an earthquake?' He said they were just gonna leave me (dangling)."