I'll tell you one thing; there is not a whole lot left of this very famous Persian War battleground, and they just built the Olympic crewing facility on top of the rest much to the dismay of many historians and outraged archeologists.
On the first day of Olympic trials 4 boats were capsized due to high winds and the German crew came down with salmonella poisoning! Way to go PASOK/Olympic Committee!!
Also the river/topography has changed through the centuries making it hard to retrace the battle.
However, a trip to Marathon and a visit to the museum and archeological site is still worth a visit. Marathon is still one of Attica's loveliest spots and only 42 km from Athens. The road passes through hilly terrain before debouching on the large and flat Plain of Marathon where vegetable gardens, vineyards, olive orchards and wild vegetation still thrive! There are also several nearby beaches which you can learn more about by clicking the beaches link above on the main menu. Schinas is the most popular beach. The ancient site of Ramnous is 12 km away from Marathon and was site to two temples.
According to Herodotus, modern historians main source of information on this battle; 100,000 Persians were defeated by 11,000 Greek Soldiers at Marathon. 10,000 were Athenian soldiers and 1000 from nearby Plataiai. The Greeks were victorious due to the ingenious plan of their general Miltiades.
After the victory, a soldier, Pheidippides was dispatched to bring Athens the news. He ran all the way from the battlefield to the Athenian Agora where he collapsed after delivering his one word message: Nenikikamen or We have Won!
Pheidippides run is the event which inspires today's Marathon runners all over the world weather they know it or not. It is also symbolized by the opening ceremony at each Olympic Games.
Buried in a single tomb, about 1 km from the road to Marathon are the remains of the 192 Athenian soldiers who died during the famous battle. 5 km away, on the other side of the road is the smaller Tomb of the Plataiians.
The museum is small and houses finds from the nearby site as well as finds from other places and periods too. Neolithic Age discoveries from Oenoe found in the Cave of Pan and 2nd C BC stelae to name a few.
By Car: take Leoforos Kifisias Ave. from the center of Athens and drive North to Marathon.
By Bus: Take the Paralia Marathonos Bus from Mavromateon St. terminal near the Pedion tou Ares park on Alexandras Ave in Athens. See the Olympic Events Map for Marathon too!