April 19, 1956, at 9:30 a.m., 600 guests at the St. Nicholas Cathedral witnessed the religious wedding ceremony at a high mass that was celebrated by the Bishop of Monaco. The flowers decorating the altar and church included white lilacs, hydrangeas, lilies, and snapdragons. It was called "the wedding of the century" by the press. It is estimated that 30 million people watched the wedding on television.
The matron of Honor was Grace's sister, Peggy. There were six bridesmaids. They all wore yellow organdy dresses. The six junior attendants (4 girls and 2 boys) were all dressed in white.
Guests included Cary Grant, Aga Khan, David Niven, Gloria Swanson, Aristotle Onassis, Ava Gardner, heads of state, and diplomats.
The people of Monaco gave the couple a cream and black Rolls-Royce convertible. The luncheon reception was held in the Palace Court of Honor. They sliced the six-tier wedding cake with the Prince's sword.
Their honeymoon was a cruise aboard the "Deo Juvante II" with stops in Villegranche, Spain, and Corsica. Grace reportedly was frequently seasick.
Prince Rainier wore a Napoleonic military type of uniform that he designed himself.
Grace's wedding gown was a gift from the MGM Studio and designed by Helen Rose. It was a high-necked, long-sleeved gown with a fitted torso and billowing skirt made of twenty-five yards of silk taffeta, one hundred yards of silk net, peau de soie, tulle and 125-year-old Brussels rose point lace. She wore a Juliet cap that was decorated with seed pearls, orange blossoms, and a veil of 90 yards of tulle. The chief hairstylist at MGM Studios, Sydney Guilaroff, styled Grace's hair for her wedding. Grace carried a small Bible and a bouquet of lilies-of-the-valley.