Prince Harry weds US actress Meghan Markle today (May 19) in a lavish ceremony that unites the pomp of British royalty with Hollywood glamour.
Hundreds of millions of people across the world are expected to tune in to watch the wedding of Queen Elizabeth's popular grandson and the American star of the TV drama "Suits" at the 15th Century St George's Chapel in Windsor Castle.
More than 100,000 fans will cram the narrow streets of the town 20 miles (30 km) west of London, dominated by the oldest and largest inhabited castle in the world, a home to 39 English monarchs since 1066.
Harry, 33, is sixth in line to the British throne. Markle, 36, is a divorcee whose mother is African-American and father is white.
For many, the wedding is a fairytale. For some black Britons, it illustrates the breakdown of barriers in modern Britain.
To others, it is an irrelevance. Polls have suggested that most Britons will not bother tuning in to watch the event.
The hour-long ceremony begins at 1100 GMT, with weather forecasts predicting blue skies and sunshine.
The bride will arrive at the church with her mother, Doria Ragland, 61, with whom she was spending Friday night at a luxury hotel. Harry was staying at another hotel with elder brother and best man Prince William, whose daughter Charlotte and son George will be among the bridesmaids and page boys.
Harry's father and heir-to-the-throne Prince Charles will walk his future daughter-in-law down the aisle after Markle's father pulled out due to ill health.
Thomas Markle, 73, a lighting director for TV soaps and sitcoms, told the US celebrity website TMZ he had undergone heart surgery on Wednesday. Confusion over his attendance marred the build-up to the wedding, which had been carefully choreographed for months by royal aides.
On Friday, Ragland met the 92-year-old monarch and her husband Prince Philip, 96, who will be among the senior royals in the 600-strong congregation. It will also include a smattering of celebrities, including fellow cast members of Markle from "Suits".
The service will be conducted by the Dean of Windsor with Justin Welby, the Archbishop of Canterbury and the spiritual head of the Anglican Church, overseeing the exchange of vows. A black US bishop, Most Reverend Michael Bruce Curry, will give the wedding address.
After the ceremony, the newlyweds are expected to greet some of the 1,200 members of the public specially invited into the grounds of the castle before setting off on a carriage procession through Windsor.
A reception will be held in the castle's St George's Hall before 200 guests join the couple at an evening event at Frogmore House, another grand mansion in the grounds.