For many years, Ava Gardner received a bottle of champagne every year on her birthday from Princess Grace of Monaco. “She never forgot, and every year at Christmas she sent a handwritten card,” wrote Ava of Grace Kelly in her memoir, Ava: My Story. “She was a great lady, and also great fun.”

Hollywood is filled with stories of costars who couldn’t tolerate each other offscreen, but Ava and Grace, who met while filming 1953’s Mogambo, shared one of the Golden Age’s sweetest friendships. “They wrote letters and would send gifts to each other,” Dean Sidden, a board member at the Ava Gardner Museum, tells Closer. “They remained close friends regardless of the physical distance between them.”

If they hadn’t both been popular actresses, it’s likely that Ava and Grace would never have met. Ava, who was born in 1922, grew up in North Carolina. The child of farmers, she spent her summers barefoot, climbing trees and running with the boys. Grace, meanwhile, was born into a prominent Philadelphia family. Despite her parents’ objections, she studied theater at the American Academy of Dramatic Arts and landed in Hollywood around 1950.

Grace Kelly and Ava Gardner Were Kindred Spirits

Director John Ford noticed Grace in one of her early films and cast her in Mogambo, a remake of 1932’s Red Dust. Clark Gable reprised his role from the original, this time caught in a love triangle between Grace and Ava rather than Mary Astor and Jean Harlow.

“Instead of being shot on the Metro back lot, it was truly going to be photographed where it was supposed to take place,” recalled Ava, who joined her costars on location in Kenya, Uganda and several other African countries.

It wasn’t an easy shoot. An uprising led the production to hire armed guards to protect the cast and crew in Kenya. The locations were also subject to overwhelming heat, torrential rain, mudslides and poor roads. “It’s hot as it can be during the day,” Grace wrote to a friend. “Was in the sun a lot today and my poor nose is like a red light.”

Frank Sinatra made the trip to visit his bride Ava on the set. Romantic sparks also flew between Grace and Clark, but the most enduring relationship would be between Ava and Grace. “I remember on Gracie’s birthday we got a bottle of champagne from some bootlegger, and she and Clark and [director John] Ford and I had a little party out in the tent. Later, we did the same thing for mine,” recalled Ava, who confided that Grace “was never much of a drinker, though she tried hard.”

Ava kept an eye on Grace, especially when she left to be sick after imbibing too much. “I’d go off and find her and bring her back before the lions ate her,” she recalled.

Grace’s romance with Clark didn’t continue beyond Mogambo’s wrap party, but her friendship with Ava would last until her death in a 1982 car accident. “To be a friend of Ava you had to be ferociously loyal,” says Bill Turnage, a board member of the Ava Gardner Museum. “Ava was devastated to lose her.”