The world's best-kept secret is finally out! HRH the Duchess of Cambridge walked down the aisle at Westminster Abbey Friday morning in a stunning Alexander McQueen wedding gown.The 29-year-old bride, who admitted to pre-wedding jitters, stepped out of the car in a fitted white V-neck gown with a long-sleeved lace overlay, designed by McQueen creative director Sarah Burton. Her two-meter, 70-centimeter train was folded next to her in the car as it transported her to the Abbey. Once she arrived, she paused for a moment – giving onlookers a peek – and sister Pippa (also in McQueen) appeared, to carry her train. The dress is composed of French Chantilly lace and English Cluny lace throughout the bodice, skirt and underskirt. The skirt, made of ivory and white satin gazar, was designed to emulate an opening flower: padded at the hips, it flowed out to the floor. The back of the dress was finished with 58 gazar and organza covered buttons fastened by Rouleau loops.Kate wore her brunette hair in curls. She topped the look with a ivory silk tulle veil, which was trimmed with hand-embroidered flowers. It was held in place by a Cartier 'halo' tiara, lent to Kate by the Queen. She also wore diamond drop earrings by Robinson Pelham, a gift from her parents. Her handmade shoes, also McQueen, were composed of ivory duchesse satin and lace. As the wedding festivities continue today, Kate is expected to change into a second (and maybe even third!) dress.