A man running backwards and a woman knitting a two-metre scarf are among thousands taking part in the London Marathon - which has seen a record-breaking win by a Kenyan runner.
Up to 36,500 competitors are taking part in 26.2-mile race, with fun runners and celebrities raise money for countless charities
Olympic rowing champion James Cracknell, models Agyness Deyn and Elen Rivas, and former Manchester United striker Dwight Yorke are among the famous faces pounding through the streets.
More than 100 marathon world records are being attempted, including the quickest person running backwards.
Get set, ready, go: Runners at the starting line
Trainee PE teacher Karl Twomey, 37, born in Dublin, admitted that preparation had been difficult.
"It's not so much neck ache, it's more landing on my butt. I've had a few falls in training. Obstacles are the problem," he said.
"I was veering in the wrong direction into poles, bins, you name it I've hit it."
Susie Hewer, 53, is hoping to knit a world-record scarf as she runs for Alzheimer's Research UK.
She said it will start to get "a bit tricky" when the scarf reaches the ground and she will have to wrap it around her waist and wear it over her shoulder.
Andy Jackson, 26, from south London, is dressed as Mr Happy in aid of Children with Leukaemia.
He said: "I've been in remission for eight years. I found out the cost of my treatment, which was £250,000. I'm trying to raise that, to give another person the same second chance of life."
Britain's very own 'Bladerunner', Richard Whitehead, is hoping to make history
Double leg amputee Richard Whitehead is hoping to make history by beating his own world record at this year's marathon.
Despite having to run on prosthetic limbs, the 34-year-old is hoping to cover the route in just 4 hours and 42 minutes.
PC David Rathband, who was blinded by gunman Raoul Moat, is running for his charity which supports emergency services personnel injured in the line of duty by a criminal act.
He said he had no finish time in mind for the marathon and was only aiming to "beat the road sweeper".
Agyness Deyn swaps the catwalk for the marathon route
The race began in Blackheath this morning and the finishing line is in front of Buckingham Palace.
Four Kenyans overpowered a top-quality field - with Emmanuel Mutai running the fastest-ever elite men's race in a record time of 2:04.40.
The 26-year-old bided his time in a tightly bunched pack until the second of the two pacemakers dropped out after 30kms.
Emmanuel Mutai breaks the marathon's course record
He then surged to the front ahead of the leading group to win unopposed.
"My dream has come true," Mutai, who finished second last year, said.
"Between 36 and 38kms it was a little difficult but I just tried to push it and in the end I managed it."
It was Mary Keitany's first London Marathon
Fellow countrymen Martin Lel, a three-time London Marathon winner, came second and Patrick Makau was third.
Compatriot Mary Keitany, 29, became the fourth Kenyan winner of the women's race, finishing in 2:19:17 - almost a minute ahead of defending champion Liliya Shobukhova.
She is now equal with Irina Mikitenko as the fourth fastest woman ever after finishing third in her marathon debut in New York last year.