What is it?
Why, it's only the 37th edition of the long-distance race around the streets of London which is tackled by both elite athletes and amateurs who regularly run the 26 mile and 385 yard course – or 42.195 kilometres for the Europhiles among us – for charitable causes.
Incidentally, the fastest ever time the course has been run in happened in 2016 when Eliud Kipchoge of Kenya completed the route in two hours three minutes and five seconds. Paula Radcliffe of Great Britain set the fastest time for a woman back in 2003 after putting in a two hour 15 mins and 25 secs shift on the streets of London.
When is it?
All races take place on Sunday April 23, 2017. First up, the wheelchair race starts at 8.55am (BST) and will be followed by Paralympic runners at 9am whose race is part of the IPC Athletics Marathon World Cup.
The elite women's race gets under way at 9.15am before, 40 minutes later, the men lead out the tens of 1,000s of amateur runners.
What TV channel is it on?
The London Marathon will be broadcast live on BBC 1, with their programme starting at 8.30am.
What does the weather forecast look like for Sunday?
For the runners the weather is looking perfect, possibly a little chilly for anybody planning on heading into central London to cheer them on.
Here's what the Met Office have to say: "A mild, but not hot, day with a light breeze will help those charity runners who will still be completing the course past noon.
"Those conditions will also help the professional runners get around the course in world-record time – as we saw in 2002 when Khalid Khannouchi shaved a few seconds off his own world-record."
What does the course look like?
Where are the best roadside spots to watch the race from?
How can I track a specific runner?
Official app and online tracker
The Virgin Money London Marathon ran its own mobile app for the first time in 2015, to make it easier for friends and family of participants to track the race as it progresses.
This year is supposed to be the first time the service will be available on Android, having previously been an iPhone exclusive.
The tracking facility is also accessible via the official website - though it is currently inactive, pending the race start. Timing intervals are every five kilometres and you can search both by a runner's name and their race number.
The app still appears to be only available on iPhone, so Android users will have to head online or use other running apps.
The official app and online timing uses the chips given to each runner, but only delivers estimated positions every five kilometres. If you want more specific feedback, it is worth exploring other options.
There is a range of other apps available on both Apple and Android that use GPS tracking and automatically deliver live updates to followers online.
These smartphone apps can provide more detailed and personal way to follow a friend than the official website. Set up before the marathon starts, the smartphone will send progress reports via email and social media throughout the race.
Some of the running apps are free, but to access the live-tracking facilities with the likes of Garmin Fit and RunKeeper you’ll have to sign up for the paid subscription service.
To avoid the battery running out mid-race, make sure you pull back to the Home screen so that the app is only operating in the background.
It’s also best to be aware that during past London Marathons, these mobile means of tracking have had problems with overload.
If you’re out on the course looking to spot a specific runner, you can also use good old-fashioned mental arithmetic to ensure you’re in the right place at the right time.
Provided your charge has done a modicum of training – enough that they can take a stab at their average minutes-per-mile – and you know what time they start, you can make a fair guess what time they’ll hit each mile marker around the course.
By Sean Gibson
London's going to be busy, but what roads will be closed?