In her best moments both on- and off-screen, Audrey Hepburn was wearing Givenchy. She and Hubert de Givenchy met in their mid-20s, and their friendship and professional partnership spanned 40 years. He designed her first Oscars dress, the black satin gown she wears in Breakfast at Tiffany’s, and a pink jersey dress for her wedding day.

“Givenchy’s creations always gave me a sense of security and confidence,” she once said, “and my work went more easily in the knowledge that I looked absolutely right. I felt the same at my private appearances. Givenchy’s outfits gave me ‘protection’ against strange situations and people. I felt so good in them.”

The book Audrey and Givenchy: A Fashion Love Affair, out April 12 from Running Press, traces their collaboration in Hollywood and in her personal life, showing timeless designs that have influenced fashion for decades. Click ahead to see looks from Funny Face, Love in the Afternoon, Charade, and more.