Powerful, enduring relationships can sometimes develop between photographers and their subjects. Such was definitely the case with LIFE's Alfred Eisenstaedt and the luminous Italian film legend, Sophia Loren. Over the course of their decades-long friendship, Eisenstaedt took countless pictures of the Oscar-winning actress — most of which never made it into the pages of LIFE magazine (and many of which were never intended for the magazine).
"Eisie must have shot thousands of pictures of me that no one ever saw," Loren told LIFE.com, fondly recalling her camera-toting "shadow." Here, LIFE.com presents a series of Eisenstaedt's finest portraits of Loren, made at the very height of her international fame.
"When I met Eisie," Loren recalled, "it was really a love at first sight. He became my shadow. But he never tried to interfere in my life. No, he just kept on shooting and smiling, and was happy just to be with me — like I was to be with him! I miss him. He couldn't do any wrong to me. I trusted him so much. He's one of those who doesn't grow on trees, as my friend Cary Grant used to say."
Asked by LIFE.com about the qualities Eisenstaedt (with Loren, at left, in 1961) was able to bring out in her that other photographers somehow missed, or simply failed to elicit, Loren considered for a while, then said: "That I was a girl, joyful for her life, because she accepted anything that came with her work. Just being really, completely happy. Yes."
Loren appeared on LIFE's cover seven times through the 1950s and '60s.
"At that time," she said, "when LIFE magazine came out every week, it was something very important for a career — the best thing that could happen to an actress. It was something unbelievable. Everybody talked about it — a story in LIFE magazine, with a cover."
In the summer of 1964, Eisenstaedt visited Loren and her husband, Carlo Ponti, at the home Ponti had spent years restoring: an opulent, ancient, 50-room villa in Marino, Italy. Several of the pictures he made there are featured in this gallery. And although Loren loved the house — at the time of Eisenstaedt's visit, she called living there "bliss" — it was sold around the time of Ponti's death, in 2007.
"This is something I don't like to live with — sad memories," she confided. "Life gets very hard when you lose someone so important to you, and you don't need to be surrounded by the memories all the time, which are so strong and hit you in the most unexpected moments. We had a great, great love. The more I go on without him, the more I miss him. It was a great feeling — it was great in life and it was great in our work."
Asked if she ever tires of fame, Loren broke into a musical laugh.
"Are you kidding? I think it's wonderful. [Fans] smile at me like I was a member of their own family. It's a great feeling. In a sense, when I am at home I feel lonely because I miss my husband. But when I am outside, I have great big families around me all the time."
Liz Ronk, who edited this gallery, is the Photo Editor for LIFE.com. Follow her on Twitter at @LizabethRonk