Stanley Kubrick's The Shining is a masterclass of cinematic art and a defining chapter in the horror genre in and of itself (even if Stephen King thinks otherwise). Since its release in 1980, the film has become something of a cultural milestone, with its iconic and terrifying visuals being referenced in every facet of pop mythology.

Everything from the creepy twins to the memorable rug decor has become famous, but there is perhaps no image as instantly horrifying as the elevator doors of ​the Overlook Hotel opening to reveal a river of blood rushing down the halls. It's an image that has haunted the nightmares of many a filmgoer and was so impressive that the studio focused the film's marketing almost exclusively around the shot.

Kubrick's longtime assistant, Leon Vitali, recently revealed in an interview just how the shot was managed. "We spent weeks and weeks and weeks trying to get the quality and of the blood as natural as it could be," the 70-year-old filmmaker told Yahoo!.

"The consistency was also quite important, because we were pouring out hundreds of gallons of the stuff," Vitali continued. "And then, of course, there were the mechanics of it, because if you have that much pressure ​inside something like an elevator, it’s going to blow if you’re not careful ... I tell you, it worked in a way we never thought it would work... It was such a violent volume of this red liquid coming at you; those of us who were in there thought, ‘My God—we’re doing to drown!'"

​Kubrick himself was apparently so anxious about the exhausting shot that he helped construct the elevator mechanism and positioned four cameras with different focuses and different frame rates, but left the room before the actual shot was done, unable to watch if something were to go wrong.

Miraculously, the shoot went off without a hitch and it became Kubrick's favorite scene. He reportedly watched it over and over in glee afterwards.