Elvis Presley made 31 films during his careeralmost all of which were wildly profitable and, creatively, mostly the same: simple romantic plots, campy humor, lots and lots of music. Released in 1964,Viva Las Vegaswas built to follow the same formula for success. Yet the results were iconically different: It not only became the highest grossing film to feature Elvis, it propelled the career of costar Ann-Margret and widened the appeal of Sin City itself. What madeViva Las Vegasspecial? It had chemistry. It had heat. It showed larger-than-life superstarsat the peak of their powersflirting and frolicking their way through life. Almost a decade before Elvis and Vegas became inseparable, this movie established why it was a match made in musical heaven. And the on-screen chemistry he shared with Ann-Margret wasnt great actingit was a real-life seduction caught on camera.