Legend states that after the Greek army defeated the invading Persian forces near the city of Marathon in 490 B.C.E., the courier Pheidippides ran to Athens to report the victory and then immediately dropped dead. The story — and the distance Pheidippides covered — inspired the modern marathon, a grueling 26.2-mile contest that attracts some 1.3 million runners annually to compete in the more than 800 races held worldwide.