2 THE DEMA FORTIFICATION WALL Ano Liosia - Fyli Access The monument is accessible only by car
The Dema fortification wall, the Dema watchtower, and the so-called “rear wall” of the Dema form a unity, given that they belonged to the same defensive system developed by the Athenians in the 4th c. BC to fortify their western borders. They are located west of the modern city of Athens, and east of the landfill of Ano Liosia and Fyli. The wall began from the northern foothills of Mt. Aigaleo and ended in the southern foothills of Mt. Parnes (Parnitha), extending to a length of 4,360 m. It is for this reason that it was known by the name “Dema”, i.e. it “bound” Aigaleo with Parnes. The watchtower is about 140 m east of the Dema wall on Pyrgathi hill, and the “rear wall” lies 225 m to the east, i.e. behind the wall. The Dema wall was constructed perpendicular to the passage created between the two mountains. The name of the passage – Kropia – is preserved in the text of the ancient historian Thucydides, who describes the Peloponnesian War (431-404 BC) waged between the era’s two major powers, the city-state of Athens and that of Sparta. According to Thucydides, the Lacedaemonians, led by their king Archidamos, invaded Attica in the first year of the war (431 BC) “through Kropia”, having Mt. Aigaleo on their right. From that time on, it formed the main road for their invasions of Attica. This was reason the Athenians built the wall at this strategic site after their defeat in the Peloponnesian War. Its monumental size, with a total original length of 4,350 m (today 3,722 m) and its peculiar mode of construction make it an exceptionally significant preserved monument, one which attracted the attention of the international community from the 19th century. It consists of two sections, the southern and the northern. The southern section extends from the northern foothills of Mt. Aigaleo northward. Rather than being continuous, it consists of individual overlapping sections: the northern ending of each section lies to the west of the southern start of the following section, forming an opening about one meter wide. In contrast to the southern section, the northern section, which extends into the southern foothills of Mt. Parnes, is continuous and straight. The form of the Dema wall is connected with the defensive tactic of trench skirmishes rather than battle on an open field, as described by the ancient historian Xenophon (Hellenica, v. 4, 9-10, 38-42, 49) in connection with fortification works in the Theban plain. The Dema wall formed a barrier to hostile armies approaching Attica from the west and northwest (the Peloponnese or Boeotia), serving to delay their advance.