Thriasian Plain

The Thriasian Plain (Greek: Θριάσιο Πεδίο, Thriasio Pedio) is a plain in western Attica, immediately to the west of Athens, in Greece. It is bounded by Mount Egaleo to the east, Mount Parnitha to the north, Mount Pateras to the west, and the Bay of Eleusina to the south.

The Thriasian Plain owes its name to the ancient deme of Thria (Greek: Θρία), one the demes of ancient Athens. The largest town in the plain was Eleusis (modern-day Eleusina), location of the famous Eleusinian mysteries. In Greek mythology, when the goddess Athena won the contest for control of Attica over Poseidon, Poseidon flooded the plain in wrath, until called to order by Zeus

In antiquity, as today, the area was connected to Athens by two passes: the Sacred Way (Greek: Ιερά Οδός) to the west, today used by the main Athens–Corinth highway, and another pass to the northwest nowadays used by the Attiki Odos highway. During the Peloponnesian War (431–404 BC) the Thriasian Plain was ravaged by the Spartan armies of King Archidamus II in his campaign against the Athenians.

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