Meghan Markle's first look as the royal bride—Watch

U.S. actress Meghan Markle set off in a limousine on Saturday for her wedding to Prince Harry at Windsor Castle, a union that supporters hope will modernise the British monarchy for the modern age. 

Royals and celebrities streamed into St George's Chapel for what was set to be a glittering display of British pageantry at the world's oldest inhabited castle. 

Here is Meghan's first look as the royal bride, as shared by Reuters on Twitter:

Meghan Markle leaves her hotel for the journey to the #royalwedding, accompanied by her mother Doria Ragland. Watch live: https://t.co/jQinniFPz4 pic.twitter.com/XYa11QvfGc — Reuters Top News (@Reuters) May 19, 2018

Hours before the ceremony, Queen Elizabeth bestowed the title of Duke of Sussex on her grandson, a step that means the American actress, star of the TV drama "Suits", will become a duchess when she marries Harry.

Under clear skies and glorious sunshine, a military band in scarlet uniforms and bearskin hats entertained thousands of excited fans gathered behind barriers. Police armed with semi-automatic rifles patrolling streets and watching from rooftops.

"It’s absolutely incredible. The atmosphere here is just going to be crazy when Meghan turns up. I’m so pleased to be here," said Charlotte Field, 21, one of 1,200 people invited into the grounds of the castle for the wedding.

Joining U.S. media mogul Winfrey and actor Clooney and his wife Amal were former soccer star David Beckham, his fashion designer wife Victoria and James Corden, the British host of the American TV chat show "The Late Late Show".

Other guests included tennis ace Serena Williams, the siblings of Harry`s late mother Princess Diana, singer Elton John, who sang at Diana`s 1997 funeral, British actor Idris Elba, and two of Harry`s ex-girlfriends.

The couple, who met on a blind date in 2016 and fell in love in a tent under the stars in Botswana, will tie the knot at the 15th-century St George`s Chapel, in a castle that has been home to 39 English monarchs since 1066.

More than 100,000 fans are expected to cram the narrow roads of Windsor, about 20 miles (30 km) west of London. Visitors had to pass through police search points set up around the castle.

Hundreds of TV crews from around the world were present for the union of Harry, 33, sixth-in-line to the British throne, and Markle, 36, a divorcee whose mother is African-American and father is white.