Marathon is a famous battlefield a few kilometers from Athens and not a mass tourism destination catering to foreigners or an ideal place to stay in one of the few hotels along the shore. Visiting Marathon should probably only be undertaken by battlefield buffs. However if you have a car or driver and want to day trip your visit. This may easily done though in winter be sure and make an early start. Athenian traffic can be time consuming all year round.
The plain of Marathon is the site of the most famous of Greek military victories which occurred in 490 BC.
This battle resulted in the defeat of an invading Persian army of almost 25,000 infantry and cavalry by a Greek force of 10,000, comprised of Athenians and Plataians.
The Persian forces had, a few days prior and en-route to their primary destination Athens, overwhelmed the city state of Eretria in Euboean quite easily, and the continued on south towards the Attic plain.
The Persian general, Datis' decision to land his fleet at the Bay of Marathon, was influenced by Hippias, whose father had landed there successfully fifty years earlier. The Athenians, in the meantime, dispatched their herald, Pheidippides to bring Spartan aid, marched to Marathon, and set up camp in the Sanctuary of Iraklis (Heraklis or Hercules), which was a strong position on the mountain road from Athens.