If you're trying to worm your way through traffic on Sunday or in the crowds at the Mall to cheer on a relative, it will be hard to picture any other race matching the sheer size and scale of the London Marathon.
Yet the scuttle through the Big Smoke is just one of the world's Marathon Majors alongside Chicago, Boston, Tokyo, New York and Berlin/
The pavements of each of those world cities take a similar pounding each year as hundreds of thousands of amateur athletes test themselves over 42 km, with elite runners such as Mo Farah - who is running in his first London Marathon in four years this year - also competing against each other over a year-long scoring system of the races as part of the World Marathon Majors championship.
Kenyan Eliud Kipchoge is the reigning champion and returns to London this weekend for the final race of Series XI after missing last year's attempt to become the first man to run a marathon distance in under two hours.
Runners are scored based on their best two race finishes and the eventual winner can take home a prize of $250,000 - half of what winners of previous series have earned.
Instead, for the first time, the second and third placed runners will be rewarded with $50,000 and $25,000 respectively.
Winning the London Marathon is worth $55,000 (£39,273) for both the male and female champions.
Winners of individual marathons also receive a healthy reward - but the amount differs from race to race. While the distance may stay the same between the six races, they differ on every other measure:
1. Finishers - New York
2. Spectators - Chicago
3. Prize money - Boston