Up to 40,000 runners will take part in this year's Virgin Money London Marathon, which is back on its traditional route from Blackheath to The Mall and open to spectators after last year's was held for elite athletes only, behind closed doors.
What is it?
It's the 2021 London Marathon. This year is the first time the event has take place on its traditional course in October, rather than the spring.
Last year’s event was also held in October but took place virtually for the mass participants and on a closed-loop circuit around St James’s Park for elite runners.
When is it?
The marathon takes place on Sunday, October 3.
What time does it start?
08.30: Mini London marathon
08.50: Elite wheelchair races
09.00: Elite women's race
09.30: Elite men's race and mass start
What TV channel is it on?
You can watch the London Marathon live on the BBC. Coverage begins at 8am on BBC Two, before it switches to BBC One from 10am to 2.30pm. There is then another 30 minutes on BBC Two between 2pm and 2.30pm.
From 2.30pm until 4pm, you can watch the marathon via the Red Button or BBC iPlayer, with highlights on BBC Two from 6pm to 7pm.
Highlights are on BBC Two between 6pm and 7pm.
On top of all that, of course, you can follow full live coverage with us through our live blog.
Who is running in the elite races?
Women’s world record holder and Olympic silver medalist Kosgei will be attempting to win her third successive London Marathon after victories in 2019 and at the elite-only race last year.
Birhanu Legese (ETH)
Mosinet Geremew (ETH)
Titus Ekiru (KEN)
Evans Chebet (KEN)
Mule Wasihun (ETH)
Sisay Lemma (ETH)
Kinde Atanaw (ETH)
Shura Kitata (ETH)
Vincent Kipchumba (KEN)
Tristan Woodfine (CAN)
Brigid Kosgei (KEN)
Roza Dereje (ETH)
Birhane Dibaba (ETH)
Joyciline Jepkosgei (KEN)
Valary Jemeli (KEN)
Degitu Azimeraw (ETH)
Zeineba Yimer (ETH)
Tigist Girma (ETH)
Ashete Bekere (ETH)
Alemu Megertu (ETH)
Sinead Diver (AUS)
Allie Kieffer (USA)
Moira Stewartova (CZE)
What are the current marathon records?
2hrs 1mins 39secs is the men's fastest time, set by Kenyan Eliud Kipchoge in Berlin in 2018.
The average time for male runners is around 3 hours 48 mins.
Brigid Kosgei set the women's world record of 2:14:04 at the 2019 Chicago Marathon.
4 hours 23 mins is the average time for female finishers.
What is the latest weather forecast?
At the moment the forecast is for sunshine and showers, with temperatures hovering in the mid teens, with a high of 16C.
How will transport be affected?
Roads will be closed across south east and central London between 4am and 7pm, while buses in central London and Greenwich will terminate early, or be diverted, from 6.30am to 7.30pm. DLR will run a changed service until 5pm.
For more information about getting around, click here.
What are the best viewing spots?
Here's what the official London Marathon website suggests…
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.
Busy areas include Greenwich town centre and the Cutty Sark. While the ship is undoubtedly a beautiful backdrop for the race, the crowds that are attracted here can make spectating uncomfortable and transport in and around Greenwich becomes particularly busy. We strongly advise spectators to avoid this area.
Tower Bridge is always extremely busy, as is anywhere from mile 24 to the finish in The Mall. Obviously many of you will eventually end up in this area later on in the day as you head to the runner meet and greet area in Horse Guards Road.
Which celebrities are running the marathon?
Here are a few of this year's celebrity participants:
Chris Newton – three-time Olympic silver and bronze medalist (cycling)
Dani Rowe – Olympic gold medalist (cycling)
Hannah Macleod – Olympic gold and bronze medalist (hockey)
James Cracknell, double Olympic gold medalist (rowing)
Joanna Rowsell – double Olympic gold medalist (cycling)
Stephen Batchelor – Olympic gold medalist (hockey)
Zola Budd – former South African 5,000m world record holder (athletics)
Chris Evans – Virgin Radio DJ
Dev Griffin – Capital FM radio DJ and TV presenter
Dick and Dom – presenting duo Richard McCourt and Dominic Wood
Saffron Barker – YouTube star and former Strictly Come Dancing contestant