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
Athletics at the 1908 Summer Olympics – Men's marathon before the Games opened it was realised that the Royal Entrance could not be used as the marathon entrance—it was raised to permit easy descent by the royal party from their carriages, and did not open onto the track—so an alternative entrance was chosen, diagonally opposite the Royal Box. A special path was made from Du Cane Road running due south just east of the Franco British Exhibition ground so that the distance from Windsor to the stadium remained "about 26 miles". The finishing line was left unchanged, but in order that more of the spectators would have a good