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 Olympic Association that the 1908 Olympics would include a marathon of about 25 miles or 40 kilometres. The British Olympic Council handed responsibility for organising the Marathon to the Amateur Athletic Association, but they had no experience at organising a road race of such a length. In late 1907, an offer was made by Jack Andrew honorary secretary of the Polytechnic Harriers to take over the task. This was accepted in February 1908, though already, in November 1907, a route of "about 25 to 26 miles in distance" had been published in the newspapers, starting at Windsor Castle and finishing