Marathon from the start at Windsor Castle to the royal entrance to the White City Stadium, followed by a lap (586 yards 2 feet; 536 m) of the track, finishing in front of the Royal Box. The course was later altered to use a different entrance to the stadium, followed by a partial lap of 385 yards to the same finish. The modern standard distance for the marathon was set by the International Amateur Athletic Federation (IAAF) in May 1921 directly from the length used at the 1908 Summer Olympics in London. An official IAAF marathon course is 42.195 km (42
2012 Olympic Marathon Course along the Victoria Embankment with the regular London Marathon course, the Olympic event also started in The Mall whilst the London Marathon starts in Greenwich, and the event followed an otherwise different course. The logistical problems behind the design of the London Marathon course (35,000 runners of mixed ability) are very different from those behind the design of the London Olympic Marathon course (100 top-class runners) hence the difference in the routes. The course for the Paralympic Marathon also had four laps which were nearly identical to the 2012 Olympic Marathon course, but avoided certain cobbled areas notably Paternoster Square,