This is the stadium at Delphi, which gives a general idea of the configuration of the stadium at Athens built in the fourth century BC. No remains of the Athenian Stadium are visible because a modern stadium was built on its site for the first officially recognized modern Olympic Games in 1896.
The word "stadium" comes from the Greek word for a measure of length called the "stade," approximately 600 feet, which was the length of the most popular and probably oldest of foot races, the stade race.