Where is Marathon des Sables annually held?

Marathon des Sables, or MdS, (French for Marathon of the Sands, also known as Sahara Marathon) is a six-day, 251 km (156 mi) ultramarathon, which is approximately the distance of six regular marathons. The longest single stage (2009) is 91 km (57 mi) long.

This multiday race is held every year in southern Morocco, in the Sahara Desert. It has been regarded as the toughest foot race on Earth. The first event of the Marathon started in 1986.

The marathon was the brainchild of French concert promoter Patrick Bauer who in 1984 traversed the Sahara desert on foot and alone. He covered 350 km (214 mi) in 12 days without encountering a single oasis or desert community along the way. Two years later in 1986 the first Marathon des Sables was run. Twenty-three runners participated in the race with Bernard Gaudin and Christiane Plumere, both of France, finishing as the winning man and woman.