Monaco, France January 1956. Prince Rainier is pictured with actress Grace Kelly after their engagement. [Getty Images]

Monaco, France, January 1956, Prince Rainier is pictured with actress Grace Kelly after their engagement (Photo by Paul Popper/Popperfoto via Getty Images/Getty Images) — see more

Monaco, France, January 1956, Prince Rainier is pictured with actress Grace Kelly after their engagement (Photo by Paul Popper/Popperfoto via Getty Images/Getty Images)

Popperfoto Paul Popper/Popperfoto