Foundations of the Tholos or Shias. Ancient Agora, Athens. Greece. The Tholos was the headquarters and heart of the ancient Athenian government. Built around 470 BC, the beehive shaped circular building had six interior columns supporting the roof and a Propylon was added in the 1st century AD. The building was the meeting place of the 50 Prytaneis (senators), a third of who were required to be to be in attendance twenty-four hours a day in case of emergencies. Accordingly they were provided with meals and sleeping accommodation in the Tholos. The Agora from 600 BC onwards was the commercial and social centre of Ancient Athens. It was here that laws were written and displayed, commercial goods bought and sold, intellectual discussions were had, and the democratic spirited was born and nurtured.