[n 1] Today it is part of East Attica regional unit, in the outskirts of Athens and a popular resort town and center of agriculture.

Here Xuthus, who married the daughter of Erechtheus, is said to have reigned; and here the Heracleidae took refuge when driven out of Peloponnesus, and defeated Eurystheus.

[6][7] The Marathonii claimed to be the first people in Greece who paid divine honours to Heracles, who possessed a sanctuary in the plain.

[11] In mythology, its name was derived from an eponymous hero Marathon, who is described by Pausanias as a son of Epopeus, king of Sicyon, who fled into Attica in consequence of the cruelty of his father.

[13] After Theseus united the 12 independent districts of Attica into one state, the name of Tetrapolis gradually fell into disuse; and the four places of which it consisted became Attic demi, Marathon, Tricorythus, and Oenoë belonging to the tribe Aeantis, and Probalinthus to the tribe Pandionis; but Marathon was so superior to the other three, that its name was applied to the whole district down to the latest times.

Although the name Marathon had a positive resonance in Europe in the nineteenth century, for some time that was sullied by the Dilessi murders, which happened nearby in 1870.

The area is susceptible to flash flooding, because of forest fires having denuded parts of the eastern slopes of Mount Penteli especially in 2006.