When Nicky Hilton got engaged to boyfriend James Rothschild in August 2014, she had no doubt in her mind which designer she'd choose for her big day. "Ever since I was a little girl I wanted Valentino to design my wedding dress. Valentino is the definition of timeless elegance, I don't think there's another couture house like it," Hilton told Bazaar over the phone from London where she's set to marry on Friday, July 10. The hotel heiress worked with the couturiers for six months to create her dream dress. "I went through every look from their collections over the last 10 years. I studied the archives, and I just sent notes about details I liked—a certain sleeve, a high neckline." The final confection was a guipure lace gown, embellished with crystals, attached to a precious balloon skirt with a 3 meter-long train—adding custom Christian Louboutin pumps inscribed with "Mrs. Rothschild" on the heels. Hilton says most of all she will miss jetting off to Paris for her fittings. Below, Bazaar shares an exclusive first look at her Valentino Couture wedding dress, and custom flower girl dresses by Marie Chantal.