The area of the Western Hills that comprises the hills of the Muses (Philopappos), of Pnyx and of the Nymphs was first inhabited in the 6th century BC, with the establishment of the Assembly of citizens (Ekklesia) on the hill of Pnyx and the launching of the Koile road, which led from Athens to Piraeus crossing the urban fabric of the area. Being integrated into the Themistoclean precinct, they became one of the most densely built sections of ancient Athens, extending to two known ancient municipalities (demoi), Melite and Koile.

The monumental complex of Pnyx, used for the meetings of the Assembly of the Athenians from the 6th until the late 4th century BC, is connected with the heyday of the Athenian democracy, since it was the superior centre of power and control throughout the course of its operation. Eminent politicians and orators, such as Pericles, Demosthenes and Aischines, have addressed the democratic population of Athens with their inspired speeches. The Assembly of the Athenians dealt with all major issues of the Athenian democracy, such as foreign policy and all other issues affecting the public interest.

Among the successive phases of the monument’s use, the one preserved today is that dating from the time of Lycurgus (330-326 BC). It is a universal monument-symbol of citizens’ freedom of expression and the incarnation of democracy, a place where the basic principles of isopoliteia (equal citizenship rights), isegoria (equality in freedom of speech) and isonomia (equality of political rights) were first formulated as the supreme good of Democracy, principles that have diachronically inspired democracies throughout the western world.

The monumental complex of the Assembly of the Athenians, the Koile road, preserved to a length of about 500 meters, the monument of Philopappos and the important sanctuaries of Musaeus and Nymphs, of Pan and Zeus, the Diateichisma (fortification wall) and the dense remains of the urban fabric of ancient municipalities (demoi), the more recent monuments of Pikionis and the Observatory, along with their unique natural environment and the panoramic view of Attica basin, determine the archaeological, architectural and environmental importance of the hills.