2012 Olympic Marathon Course laps, finishing at the start point. It follows the Victoria Embankment towards the City of London where it takes a winding route and continues eastwards to Tower Hill. At this point there is a U-turn and the route heads westwards, again using the Embankment as far as the Palace of Westminster and thence back to The Mall. The last three laps are identical and are exactly 8 miles (12.875 km) each. The first lap, which only incorporates the south-western section of the route, is 2 miles and 385 yards (3.571 km) long. A summary of the course and associated distance
2012 Olympic Marathon Course as 42.195 km and specifically state that the course must not be less than this distance. The rules further state that in Olympic competition the standard distance may not be exceeded by more than 0.1%. In order for a marathon performance to be ratified as a world record by the IAAF, the course must also meet other criteria that rule-out "artificially fast times" produced on courses aided by downhill slope or tailwind: the distance between start and end points when measured in a straight line should not exceed 50% of the length of the course (21.092 km in the case