Royal Parks Half Marathon
12,000 people have been taking part in this year's Royal Parks Half marathon.
It's hoped 3 million pounds will be raised for charity.
The route started in Hyde Park at 9.30am, as well as passing through St. James's Park, Kensington Gardens and Green Park.
Hyde Park also marks the finish line.
Around 40,000 people went along to support the runners and walkers taking part.