Nearly 1,500 runners from more than 50 countries took part in the 23rd Great Wall Marathon in northern China on Saturday, tackling one of the sport's most demanding courses across steep stone steps, mountain roads and rural villages. The marathon, held in Huangyaguan, is considered one of the toughest in the world, taking runners over 5,164 steps on the ancient fortification. The event, first held in 1999, has grown from about 350 runners into an international race that has drawn tens of thousands of participants over the years. #china #greatwall #Huangyaguan #marathon #race #running