The most direct way from Athens to Thebes led from Chassia up Parnes by a difficult pass to the W of Harma and the deme of Phyle, over the watershed into the Skourta plain, and thus to Thebes. This was the route taken, in reverse, by Thrasybolos in 404-403 B.C. when he brought his followers from Boiotia to Phyle and later to Peiraeus . In the 4th c. B.C. an ephebic garrison was stationed at Phyle (Dem. De cor. 38 and IG II2 2971). The fort was captured by Kassander, retaken in 304 by Demetrios (Plut. Dem. 23.2: surely katastreya/menos does not have to mean 'pulled down';), and returned to Athens. It continued to be used by the ephebes in Hellenistic times.
To guard this important pass, the Athenians built a compact, well-sited, naturally defended fort early in the 4th c. B.C. In style quarry-faced isodomic ashlar, the outside face still stands to a maximum of 20 courses, strengthened by towers, the one immediately N of the main gateway circular, the others rectangular. Linking these towers was a rampart walk, defended by an embattled parapet of embrasures and buttressed merlons covered with heavy coping blocks. Within the fortification, on its flat summit, are the slight remains of several buildings. From this citadel the guards could sigual directly to Athens. (C.W.J. ELIOT) Chronique des Fouilles linkWikidata ID: Q1552834
Info: Princeton Encyclopedia
(Princeton Encyclopedia of Classical Sites, from Perseus Project)