In pre-classical times (before the 5th Century BCE), the Areopagus was the council of elders of the city, like the Roman Senate. Like the Senate, its membership derived from those who had held high public office, in this case that of Archon. In 462 BC, Ephialtes put through reforms which deprived the Areopagus of almost all its functions except that of a murder tribunal.
In an unusual development, the Areopagus acquired a new function in the 4th Century BC, investigating corruption, although conviction powers remained with the Ecclesia.
The Areopagus, like most city-state institutions, continued to function in Roman times, and it was at that location that Saint Paul delivered the famous 'Whom therefore ye ignorantly worship, him declare I unto you' speech, after seeing an altar 'to the Unknown God'.
The term "Areopagus" also refers to the judicial body of aristocratic origin, the power of which was enhanced by Solon, or the higher court of Greece.