The length of a marathon was set to give it a convenient finishing line in London.

White City [is a] famous stadium in Shepherd's Bush, northwest London, completed in 1908 as part of a complex for the Franco-British Exhibition. That same summer it staged the fourth Olympic Games, and it was here that the modern length of the marathon was fixed at 26 miles 385 yards (42.195km). The length was originally planned at 26 miles (41.84km), but the extra yards were added to bring the finishing line before the royal box.