The London Marathon will be keeping everyone on their toes, but many parts of the capital will be at a standstill.
More than 45,000 runners will today tackle the 26.2 mile race, raising millions of pounds for charity in the process.
Sir Mo Farah, 40, will be among the elite marathon runners for the final time but it's not just about sporting greats and their personal bests.
Many do it in weird and wonderful fancy dress costumes, even more reason to back people taking on the formidable route.
While their pathway is clear, the same can't be said for those coming out to support them.
Those who want to spend the day in London need to be aware on a very large number of road closures, with the knock-on effect of public transport problems.
If you're heading there yourself and not staying in and avoiding the rain, there's a lot to know.
Mirror Online take a look at the road closures and transport problems facing millions today.
What time does it start and end?
- 09:15 Elite wheelchair races
- 09.25: Elite women's race
- 10.00: Elite men's race and mass star
The incredible race will last all day, but any runners crossing the finishing line after 4.30pm will not receive a medal.
It all begins in Greenwich before moving towards Tower Bridge, roughly the midway point of the race.
Then comes Canary Wharf before Victoria Embankment and Westminster as the iconic London Eye comes into view.
Finally, they will pass Big Ben and the Houses of Parliament. They know it's nearly over at The Mall with the finish line finally arriving at Buckingham Palace.
Public transport information and travel advice
It will be a day of big disruption across the capital with the best way to get around via the Tube, overground and DLR stations situated around the route.
A large number of bus routes will either be cancelled or diverted as a result of the road closures.
It is always important to check and the latest details can be found via the TFL site here.
Stops near the marathon route are likely to be very busy but more services are expected to run to help cope with demand.
The Tube is expected to be busy, TFL is warned - with the Jubilee, Circle and District lines are likely to see thousands more people than usual on a Sunday.
A number of national rail stations also border the route and will be running to a normal Sunday service.
The Uber Boat by Thames Clippers is also available for various stops along the River Thames.
Road closures
A number of roads along the route will be closed at different times throughout the day and here's the full list
Charlton Way, Greenwich: 4am to 1pm
Shooters Hill Road: 4am to 1pm
Charlton Park Road: 4am to 1pm
Old Dover Road: 4am to 1pm
Little Heath: 7am to 1pm
Charlton Park Lane: 7am to 1pm
Artillery Place: 7am to 1pm
John Wilson Street: 7am to 1pm
Woolwich Church Street: 7am to 2pm
Woolwich Road: 7am to 2pm
Trafalgar Road: 7am to 3pm
Creek Road: 7am to 3pm
Evelyn Street: 8am to 4pm
Surrey Quays Road: 8am to 4pm
Salter Road: 8am to 4pm
Brunel Road: 8am to 4pm
Jamaica Road: 8am to 4pm
Tower Bridge: 8am to 7pm
The Highway (south side): 8am to 7pm
Narrow Street: 8am to 7pm
Westferry Road: 8am to 7pm
East Ferry Road: 8am to 7pm
Marsh Wall: 8am to 7pm
North Colonnade: 8am to 7pm
Poplar High Street: 8am to 7pm
Commercial Road: 8am to 7pm
The Highway (north side): 8am to 7pm
Byward Street: 7.30am to 8.30pm
Upper Thames Street: 7.30am to 8.30pm
Victoria Embankment: 7.30am to 8.30pm
Birdcage Walk (westbound): 6am on April 21 to May 18
Birdcage Walk (eastbound): 7.30am on April 22 to May 18
