TODAY'S London Marathon has already broken the record for money raised as it passes the £1billion mark.
Here's what you need to know about the event Prince Harry called the "biggest one-day fundraising event on the planet", what the route is, and how to watch the marathon.
When is the London Marathon 2019?
The Virgin Money London Marathon is TODAY, Sunday, April 28.
Organisers say that about 42,000 runners are taking part in the “legendary 26.2mile challenge”.
They include “both the very best marathon runners in the world and thousands of first-timers who have been inspired to get active and raise money for charity.”
It includes elite runners - such as Britain's Mo Farah - as well as celebrities and the general public.
Andy Murray, 31, the official starter of the event in 2019, said: “It’s an honour to be asked to start the London Marathon.
"It’s such an amazing race that means so much to so many people. It raises millions each year for charity and helps inspire people to get active.
"I have nothing but admiration for everyone who runs - I may even run it myself one day.”
Murray, who is currently rehabilitating after surgery on his right hip, has a personal connection with the event as he was there to support his wife Kim when she ran in 2014.
What is the route and how can I watch it?
The London Marathon starts from Blackheath in Lewisham and finishes on The Mall. All eyes will be on Mo Farah at the head of the elite field on April 28.
Runners will be hoping for a fine spring day to help them around the 26.2 mile course.
The mass race begins at 10.10am from Blackheath and Greenwich Park.
Blue, green and red are the colours used for the coded starts covering different groups.
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The start times for the 2019 Virgin Money London Marathon are as follows:
9.05am – Elite Wheelchair Races
9.15am – World Para Athletics Marathon Championships Ambulant Athletes
9.25am – The Elite Women's Race
10.10am – The Elite Men's Race, British Athletics & England Athletics Marathon Championships and Mass Race
The Virgin Money Giving Mini London Marathon starts at Old Billingsgate at 8.40am – consisting of three-mile races for different youth categories.
This year’s London Marathon will host the 2019 World Para Athletics world championship marathon races.
And there will, of course, also be celebrities from the worlds of TV, show business, film, music, sport and media – all aiming to raise as much money as possible for their chosen charities.
The BBC is covering the marathon on TV and radio.
The course winds its way through many parts of the capital, including Woolwich, Greenwich, Rotherhithe, Bemondsey, along Tower Bridge and Westminster.
says a pub is always a “popular choice” to watch the race.
The says it’ll be busiest at Greenwich town centre, the Cutty Sark, Tower Bridge, and “anywhere from mile 24 to the finish in The Mall”.
Organisers add: "If you want to follow your loved ones and try to get a glimpse of them as they pass, we suggest that you avoid very crowded areas, where it can be difficult to find a viewing spot, hard to move around and tough to get in and out."
What did Prince Harry say about this year's London Marathon?
The Duke of Sussex, who is patron of the London Marathon Charitable Trust, said on April 18: “The London Marathon is an extraordinary force for good.
"It’s the biggest one-day fundraising event on the planet and helps hundreds of charities both at home and abroad, providing vital services to those that need them the most.
“This year’s Virgin Money London Marathon will see the total raised for charity surpass a record-breaking £1billion.
MORE ON THE LONDON MARATHON
"For every runner that has contributed to this and for those of you taking part this year, Thanks a Billion.”
Hugh Brasher, event director of the event, said that breaking the £1billion mark was a "phenomenal achievement.
"We would like to thank every runner, supporter, donator, charity volunteer, sponsor, spectator, staff member and everyone else who has contributed to this wonderful total."