The London Marathon is a long-distance running event, the world’s largest marathon as of 2012 with 36,748 finishing the race, held in London, United Kingdom. The event was first run on March 29, 1981 and has been held in the spring of every year since. Since 2010, the race has been sponsored by Virgin Money, as the Virgin London Marathon. This is the 33rd edition of the event. This event airs 4/21 @ 4:00amET/1:00amPT.