Billy Zane takes on the role of sneering steel heir Cal Hockley, Rose DeWitt Bukater's (Winslet) fiancé and the "sharpest point" of a love triangle involving DiCaprio's poor artist Jack Dawson.
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Zane sat down with Digital Spy to discuss the merits of Cameron's costly 3D conversion and why Titanic became a box office phenomenon.
"3D is not an arbitrary choice. It's not a crass, commercial endeavour," he said. "It's really good and it really differentiates. If you think you know the film, you're about to see it again in a way that engages you like never before."
The actor revealed that he felt the large-scale production was "more than a movie" from the first moment he walked on set: "They built a city to make a film. It was absurd, unlike anything I've ever seen.
"They engaged industrial engineers along with artisans, cranes were moving along the skyline every day, thousands of people building, always painting, always constructing. It was stunning."
Titanic returns to cinemas on April 6.
Photo gallery - view pictures from the Titanic 3D premiere below: