The most common version of the story has that he ran 26 miles to Athens to tell the Athenians that their navy had defeated the Persians in the battle of Marathon (490 BC) after which he collapsed of exhaustion, and died. Certain sources have him not only running to Athens but also then running back to Marathon to deliver another message to the Athenian commanders.
Herodotus states that the "professional runner" was sent with a message asking for aid all the way to Sparta (over 140 miles) and back, making the initial run in two days. Herodotus also states that Phidippides met with Pan on his return journey near Mount Parthenium.