The 4th century BC Altar of Zeus Agoraios. Ancient Agora, Athens. Greece. Made of white marble, the altar is believed to have been moved from the Pnyx during the Augustan period (1st century). 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.