Map of downtown Rome during the Roman Empire showing the Stadion at the right

The stadion (or stade) was an ancient foot race, part of the Olympic Games and the other Panhellenic Games.

The stadion was named after the building in which it took place, also called the stadion. This word became stadium in Latin, which became the English word stadium. There were other types of foot races, but the stadion was the most prestigious; the winner was often considered to be the winner of an entire Games. Though a separate event, the stadion was also part of the ancient pentathlon.

At the Olympic Games, the stadion (the actual building) was big enough for twenty competitors, and the race was a 200-yard (about 180-meter) sprint. The race began with a trumpet blow, but there were officials (agonothetes) at the starting blocks to make sure there were no false starts. There were also officials at the end to decide on a winner and to make sure no one had cheated (if the officials decided there was a tie, the race would be re-run). Runners started the race from a standing position, probably with their arms stretched out in front of them, instead of starting in a crouch like modern runners.

The stadion (pl. stadia) was also a widely used unit of length in the ancient world, see ancient weights and measures.

In German, "stadion" is still the word for stadium.