Kate Middleton and Prince William have welcomed the Tour de France to Yorkshire, as the first UK leg of the world's great cycling race gets underway.
The Duke and Duchess were joined by Prince Harry to welcome the world's best cyclists for the "Grand Depart" of the 101st Tour de France.
The Red Arrows also held a spectacular aerial display.
Cyclists gathered outside the 18th century stately home Harewood House, where they took off their helmets as they were greeted with a rendition of the French and British national anthems, performed by the Band of the Corps of the Royal Engineers.
The Duke, the Duchess and Prince Harry chatted with the lead riders, including British reigning Tour de France champion Chris Froome. Then Kate cut the ribbon to officially start the race.
Tour De Yorkshire: Leeds To Harrogate
Loud cheers erupted from the crowd as the RAF's Red Arrows performed a flyover that left a trail of red, white and blue vapour - the national colours of France and the UK.
Cycling fever has gripped the nation and hundreds of thousands of fans lined the streets of Leeds to watch the start of the race.
Spectators flocked from all over the country to cheer on Froome as he hopes to retain the winner's famous yellow jersey he won last year while excited locals will be hoping fellow Brit Mark Cavendish will pedal to victory in the first stage in his mother's home town of Harrogate.
The 198 racers enjoyed clear skies and bright sunshine as they left Leeds town hall at 11am in a leisurely ceremonial start, and began racing in earnest when they departed Harewood House.
Riders will pedal 190.5km from Leeds to Harrogate, weaving through the Yorkshire Dales and Moors and taking in three ferocious climbs.
Tomorrow they will arrive in York for a stage taking in some of the most challenging climbs in Britain, ending in Sheffield.
On Monday, the Tour moves south to Cambridge with a stage ending beneath the gaze of Buckingham Palace on The Mall in central London - which was also the final finishing line in the 2012 London Olympics cycling road race.
The Tour then goes to Ypres in Northern France to mark 100 years since the outbreak of the First World War.
After 21 stages and some 2,272 miles, riders will finish on the Champs Elysees in Paris on July 27.
Britons have won the past two Tours, and the nation is hoping we can continue our reign of dominance and retain the title.
Sir Bradley Wiggins, 34, claimed the crown in 2012 becoming the first British winner of the toughest cycling race on the planet, while Froome, 29, sped to victory last year.
The nation will be crossing its fingers that three is the magic number and Froome, who is the overwhelming favourite, can defend his title.
Up to three million people are expected to watch the Tour's two-day visit to Yorkshire.
Deputy Prime Minister Nick Clegg, who represents the Yorkshire constituency of Sheffield Hallam, and was at Harewood House to see the start, used Twitter to urge viewers watching the race to get on their bikes.
He wrote: "All eyes are on Yorkshire today for #TDF #GrandDepart - but if we want a lasting legacy we need to get more people cycling."