The Ekklesia (Citizens' Assembly)
All Athenian citizens had the right to attend and vote in the Ekklesia, a full popular assembly which met about every 10 days. All decrees (psephismata) were ratified by the Ekklesia before becoming law.
As a rule, the Ekklesia met at its own special meeting place known as the Pnyx, a large theater-shaped area set into the long ridge west of the Acropolis. In theory every assembly represented the collective will of all the male citizens of Athens, although the actual capacity of the Pnyx never seems to have exceeded 13,500, and for much of the Classical period it held only about 6,000.

Throughout its long history the Pnyx had three major building phases. The earliest is generally associated with the Kleisthenic reforms. The second phase is dated to about 404/3 B.C., a time after the Peloponnesian War, when the democracy was abolished and Athens was under the control of the Thirty Tyrants, installed by Sparta. According to Plutarch, the Thirty had a specific political reason for shifting the orientation of the seating:
The Thirty afterwards turned the bema [stand for speakers] in the Pnyx, which was made to look at the sea, toward the land, because they thought that naval supremacy had been the origin of democracy but that tillers of the soil were less ill disposed toward oligarchy (Life of Themistokles 4).
The excavators associated this passage with a large stepped retaining wall designed to support a seating area that no longer followed the natural slope and that had the bema to the south, facing inland. In a third and final phase dated to the late 4th century B.C., the seating capacity was greatly increased, to accommodate as many as 13,500 people.
In an important democratic innovation, pay for attending the Ekklesia was instituted in about 400 B.C., thereby ensuring that everyone, including citizens of the working classes, could afford to participate in the political life of the city. Bronze or lead tokens were issued to those attending the meeting, and these could later be redeemed for the assemblyman's pay of two obols (one-third of a drachma) per session.