With planned road closures in the capital and disruptions on the London Underground and Overground, spectators at Sunday's London Marathon may find their journey hindered as they try to find a prime race viewing spot.
Some mile markers on the route are particularly advantageous for spectators, as runners pass the same point twice as the route overlaps.
However, this year a few popular viewing spots are restricted, due to building works currently taking place.
Here's everything you need to know about the best spots to watch runners during the marathon:
London Marathon route map
The Virgin Money London Marathon has shared a map of the route, as seen below.
The map features details including when the route overlaps, each mile marker and the locations of all the water and Lucozade stations.
You can download a pdf of the route map by clicking on the link here.
Best viewing spots
Near the start of the race
If you head to an area near the beginning of the race in Charlton or Woolwich, then you won't have to wait long to see friends or loved ones who are taking part.
This year, the mass race is commencing at 10.10am.
The exact starting location of participants will vary, depending on which colour category they've been placed in.
However, by mile three, on John Wilson Street near Woolwich Dockyard station, the blue, red and green runners - denoting the different ability categories those taking place are divided into - will converge.
You can track runners by entering their running number on the Virgin Money London Marathon app, available to download on iPhone and Android.
Miles 14 to 21
Miles 14 to 21 of the London Marathon provide spectators with lots of opportunity to watch runners during the race as they pass through Canary Wharf.
There are several DLR stations that will take you straight into the heart of the region, including Limehouse, Westferry, West India Quay, Canary Wharf and South Quay.
While the viewing spot at Heron Quay roundabout by mile 15 tends to be a popular viewing spot during the marathon, this year it won't be accessible, due to a large-scale building project taking place in Canary Wharf.
If you do find yourself by mile 15, a London Marathon marshal will be able to suggest an alternative viewing spot for you.
Building works are also taking place in two locations near the 18-mile point on Marsh Wall.
Busiest viewing spots
Certain viewing locations along the London Marathon route become far busier than others.
While that doesn't necessarily mean you should rule them out, you should plan ahead if you'd like to try watching the marathon from these locations.
One of the most popular and recognisable points of the marathon is Tower Bridge, where runners pass the 20-mile mark.
Many spectators will arrive in this area during the early hours to obtain a spot along the famous landmark.
The area around mile seven in Greenwich is likely to become busy quickly, what with the novelty of the Cutty Sark ship in the town centre.
"We strongly advise spectators to avoid this area," the Virgin Money London Marathon states.
The large crowds may also cause a hindrance on public transport, making it more difficult to travel to and from this location.
Near the finish line
While it may be tempting to head on over to the finish line of the marathon, unless you have tickets for the Grand Stand at the very end, it will be difficult to see anything.
Miles 24 to 26, which stretch from Blackfriars to St James's Park, are likely to attract large crowds throughout the day.
Where to go after the marathon
Once the marathon is over, you'll be able to meet up with friends or family who have taken part at the meet and greet area in Horse Guards Parade.
Various points in Horse Guards Parade will be marked with letters of the alphabet.
Prior to the race, spectators and runners can decide which letter to select for their meet up area.
How may your journey be disrupted?
On Sunday 28 April, there will be no service on the Circle Line on the London Underground.
There will also be no service between Edgware Road and High Street Kensington on the District Line, no service between Aldgate and Wembley Park on the Metropolitan Line and no service between Moorgate and Hammersmith on the Hammersmith and City Line.
On the London Overground, there will be no service between Camden Road and Shepherd's Bush or Richmond until 12pm, and no service between Gospel Oak and Barking until 1pm.
Transport for London states that it expects to run a good bus service over the weekend, although buses may be delayed due to road closures.
For a map of all road closures on the day of the marathon, click here.
For all the latest news on the London Marathon, click here.
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