The name Pnyx comes from a Greek word suggesting a place packed tightly with people, and that is exactly what it was. Beginning as early as 507 BC, when the reforms of Cleisthenes shifted political power to the citizenry, Athenians climbed this hill to hold their ekklesia, the popular assembly. The site sits less than a kilometer west of the Acropolis and looks down on the ancient Agora, the city's commercial heart. Roughly six thousand men could stand on the bare rock that sloped up before the speaker's platform, a number scholars take as a fair estimate of the politically active citizens of Athens. They were not a parliament of professionals. They were farmers, potters, sailors, and shopkeepers, summoned to debate the business of the state in the open air, within sight of the Parthenon.

Stand at the bema and you stand where the greatest orators of the ancient world made their case. Pericles spoke here during the city's Golden Age, as did Aristides and the brilliant, mercurial Alcibiades. A century later, Demosthenes mounted this same platform to hurl his famous warnings against Philip II of Macedon, speeches so fierce that the word "philippic" still means a blistering verbal attack. The Pnyx embodied a principle the Athenians prized above almost all others: isegoria, the equal right of every citizen to speak. In theory, all could rise and be heard, with one custom granting citizens over fifty the right to speak first. In practice, few had the nerve or skill to face the crowd, and a citizen whose proposal proved illegal could later be prosecuted for it. Free speech here carried real weight, and real risk.

The hill the Athenians used was, in the words of one description, a "mainly natural hollow," and they reshaped it over time. In an early phase, the audience faced a platform on the north. Later, probably in the late fifth century BC, the whole auditorium was reversed: a great stepped retaining wall was raised, earth was hauled in to form a level terrace, and the people now faced a bema cut from the living rock to the south. In the fourth century BC a defensive wall with seven towers guarded the area. Scholars suspect the Pnyx, with its curved tiers of standing room facing a single focal point, may have been the prototype for the Greek theater. Democracy and drama, it seems, were shaped by the same instinct for gathering a crowd around a voice.

Athenian democracy was never guaranteed, and the Pnyx witnessed its darkest hours as well as its triumphs. During the strain of the Peloponnesian War, popular government was suspended in 411 BC and again in 404 BC, when Sparta installed a brutal junta remembered as the Thirty Tyrants. Yet in 403 BC the democrats returned, and the assemblies on the Pnyx resumed. Even after Athens lost its independence to Macedon following the battle of Chaeronea in 338 BC, the city clung to its democratic forms for generations. Excavations begun in 1910 and expanded in the 1930s under Homer Thompson confirmed the site and uncovered the foundations of later monuments, including, just to the west, the heliotropion of the astronomer Meton, where in 432 BC he worked out the 19-year cycle still named after him.