Karen Allen is astonished that people still take an interest in 'Raiders of the Lost Ark' 40 years after the film was released.

The 69-year-old actress starred in the first 'Indiana Jones' film as Marion Ravenwood, the plucky love interest of Harrison Ford's iconic archaeologist, and she confessed that it blows her mind that the film is captivating audiences four decades after it was released.

Karen said: "It's extraordinary! The fact that people are still seeing the film, talking about the film, having an interest in the film, it's amazing.

"It's amazing, and wonderful. It's just one of those films that seems like it gets passed from generation to generation, and is stayed very beloved."

Karen described her character as "tough but not heartless" and "fantastically fun" to play alongside Harrison's Indy.

The 'Starman' actress told PEOPLE: "She walked that edge of being tough, but not being heartless.

"And their relationship too, there was love underneath all of their edginess with each other. And those are fantastically fun characters (to play), if you can find something as colourful and interesting as a woman who drinks 300-pound men under the table."

Karen revealed that she knew very little about the part until director Steven Spielberg asked to meet her.

She recalled: "Steven came to New York City to meet, not just me, but some other actors he was interested in meeting for the film.

"I didn't know anything about the film. They were being very secretive about it. ... They gave me the scene in the bar, and then I was in love. I fell in love with Marion, and then I really wanted the role."

Allen explained that she auditioned alongside several other actors as film bosses didn't expect to land Harrison due to his 'Star Wars' commitments.

She said: "I went out (to LA) and I screen-tested with Tim Matheson, who had been in 'Animal House' with me.

"And I screen-tested with a New York actor named John Shea, who I knew a little bit. And they asked me to do the role a few weeks later. Harrison was not even a thought in their mind, because he was Han Solo."