The Athenian and Eleusinian (Thriasian) plains are separated by a chain of hills, chiefly Mt. Aigaleos, that runs S from Mt. Parnes to the sea W of Peiraeus and opposite Salamis. Communication between them is largely confined to a narrow S gap, through which passes the main motor road from Athens to Eleusis past Daphne, the ancient Sacred Way, and to a wide N gap between Aigaleos and Parnes, which until recently carried only the railway and a dirt track. It was through the latter that Archidamos led the Spartans in the first year of the Peloponnesian War (Thuc. 2.19.2); Agis presumably used the same route in 413 B.C. on his way to Dekeleia (Thuc. 7.17.1).
Across this N gap, at its narrowest point, is the Dema wall, a barrier built along the line of the watershed between the two plains, and planned to oppose a force coming from Eleusis. This basically rubble fieldwork is 4,360 m long, and for the S two-thirds of that length it is made up of 53 short stretches of walling, separated by openings, which, because all but two stretches overlap each other from S to N, have the form of sally ports. The two exceptions are gateways. Throughout this section the wall is massive, with a broad rampart that at times stands as much as 2 m above the ground to the W. The N third is quite different and looks unfinished. Here the line of the rubble wall is unbroken: on the lower slopes only the foundation course is apparent; on the higher slopes there are remains of a crude breastwork.
The date of the Dema's construction cannot as yet be determined with any precision. What little evidence there is might seem to favor a date in the second half of the 4th c., but a date in the first half of the 3d must also be considered a possibility. And in this period of a hundred years several occasions, from the threat of Philip after Chaironeia to the Chremonidean War might have prompted so large an undertaking. Without new evidence a choice between this or that event is probably unjustified, especially since the wall could have been built after Chaironeia and then later manned by the Macedonians.
Thirteen m to the W of the Dema wall, at the foot of Aigaleos and immediately N of the railway are the important remains of an isolated country house of the late 5th c. B.C., now buried beneath city refuse. Low rubble walls that formed socles for mudbrick outline a large rectangular structure (22 x 16 m) with the main rooms facing S onto a court through a colonnade. Ceramic evidence shows that the house was inhabited for only a short time. Historical considerations make it likely that this habitation took place between the Peace of Nikias, 421 B.C., and the Spartan occupation of Dekeleia in 413 B.C.
Three km farther W, on the highest point of a spur that lies within the pass, are the remains of a fortified enclosure known as the Thriasian Lager. The circuit contains eight towers; within are foundations of a number of buildings; a narrow fieldwork runs from the fort SE down the slope to the line of the railway. This military complex appears to be contemporary with the Dema wall, and may have been built by a force planning to invade the Athenian plain. (C.W.J. ELIOT) Wikidata ID: Q61890932Trismegistos Geo: 60780
Info: Princeton Encyclopedia
(Princeton Encyclopedia of Classical Sites, from Perseus Project)