Princess Eugenie has arrived at St Georges Chapel for her wedding to Jack Brooksbank.
The bride walked up the steps in a low-back dress and a crown in front of a host of celebrity and royal guests.
A star-studded congregation of 800 people will watch the Queens granddaughter wed tequila brand ambassador in Windsor Castles 15th century church.
Her excited husband-to-be could be seen looking nervous by the alter.
The Queen and the Duke of Edinburgh and the Prince of Wales has joined the Duke and Duchess of Cambridge and the Duke and Duchess of Sussex among more than 40 members of the Royal Family gathering for the celebration.
Among those taking their VIP seats in the chapel were entertainer Robbie Williams, Hollywood actress Demi Moore and supermodel Naomi Campbell.
Former Take That singer Williams, who got a cheer from the crowds when he arrived in a limousine and waved back, was with his wife and fellow X Factor judge Ayda Field.
Their six-year-old daughter Theodora is one of the bridesmaids.
Kate Moss, wearing a delicate monochrome polka dot outfit, took her seat on the front row of the seating plan which is designed to face into the aisle.
Singers James Blunt and Ellie Goulding arrived at the wedding in the same coach to join other guests including screenwriter and Downton Abbey creator Julian Fellowes, model Pixie Geldof, Prince Harrys ex Chelsy Davy, comedian Jimmy Carr and artist Tracey Emin.
Windsor was expected to escape the worst of Storm Callum, but conditions were very blustery as the guests arrived, with many holding on to their hats.
One man was even seen to gallantly chase after a fellow guests hat as it blew off and rolled along the ground.
The gothic chapel was filled with autumnal flowers, chosen by Eugenie to evoke the rich and vibrant tones of the season.