The wall surveyed in this article is a continuous defensive fieldwork in north-western Attica, situated some six miles from Athens; it closes a prominent gap in the mountain-ring around the city, linking the ranges of Aigaleos to the south and Parnes to the north (Fig. 1). The local name for this wall, Τὸ Δέμα ‘The Link’, is both apt and specific and is being used in this article; in the past the wall has sometimes been referred to as the Aigaleos–Parnes wall and sometimes also as the Ano-Liosia wall from its relation to the nearest modern village.
The lack of a detailed survey of the Dema, combined with a complete absence of literary references in ancient authors, has compelled earlier writers to base their theories largely on grounds of historical probability. The divergences in their conclusions are not surprising, and clearly demonstrate the need for detailed information about the remains. We have accordingly made a field survey of the Dema and offer a full description of the wall in the belief that this will lead to a truer interpretation of its function and also its date.