Take a look at our guide to the London marathon - how it all began, how much money has been raised and many more fun facts and figures.
In 1981 former Olympic champion Chris Brasher and welsh athlete John Disley, created the London marathon. Chris took part in a race in New York two years before and was so inspired by so many people from around the world taking part, he wanted to see if they could do the same in London. On the 29th March 1981, 20,000 people applied to run, 6,747 were accepted and 6,255 finished the race.
The race is 26.2 miles and the course has been rarely changed with slight changes to prevent injury. Every year without fail there are a record number of applicants and people dressed in everything from robots, fire engines and even rhinos.
Raising money has been the main goal for thousands of runners taking part. Overall there have been thirty three marathons and a massive £450 million made, making it the biggest yearly fund raising event worldwide.
It attracts all types of celebrities including Richard Branson (above), Gordon Ramsey, Susanna Reid and many more including Michael Owen, who will be running on Sunday.
The talking point in this years marathon, has to be Mo Farah Olympic gold double winner, who is making his full marathon debut. Despite collapsing last month after a half-marathon in New York, Mo Farah feels that he is ready and will be aiming for a British record breaking time.
Wilson Kipsang Kiprotich broke world record for the fastest time in Berlin last year, finishing in 2 hours 3 minutes 23 seconds. He will be wanting to duplicate that performance on Sunday and come first for a 2nd time in his career.