Travelling from Athens to Eleusis, one encounters the Thriasian plain on the Sacred Way’s right side. Encircled by Cithaeron to the north, Mount Egaleo to the east, Mount Pateras to the west, and Mount Parnitha to the northeast, the plain is traversed coastally by the Sacred Way along the Eleusis gulf. This primary route linking Athens to the Thriasian plain gave rise to the term “Thriasiai Pylai” (Thriasian Gates) for Dipylon, the Sacred Way’s commencement point in Kerameikos.
The plain, rich in agriculture with abundant grain, vineyards, and olive groves, benefited from the waters of the Eleusinian Cephissus. Its agricultural significance is mirrored in mythology, crediting Demeter with introducing agriculture here first.
Mythology also informs the name “Thriasic plain”. One narrative attributes it to the Thriae, winged nymphs skilled in divination using pebbles (thriae) in water, from whom Athena learned the art, inciting Apollo’s wrath. In response to this rivalry, Zeus affirmed Apollo’s sole right to divination. Agitated by this decision, Athena dispersed the pebbles across the plain. Another story traces the name to the fig leaf (thrion), rooted in the legend that Demeter gifted the first Attican fig tree to Phytalus in gratitude for his hospitality. A third interpretation links it to the hero Thriasios, venerated in the area as archaeological evidence in the east suggests.
The populous deme of Thria, encompassing the Thriasian plain’s eastern portion, remains an enigma in terms of its precise location. Aspropyrgos is hypothesised as its centre, though this is uncertain. Thria’s boundaries included the Rheitoi lakes, exclusive suppliers of fish and eels to Demeter’s priests, and were demarcated by the temples of Apollo Daphnephoros and Aphrodite on the border with the Hermos deme.
Agricultural activities on the Thriasian plain continued unabated until the early 20th century. However, the onset of industrialization and the establishment of Elefsina’s military airport transformed the region significantly.