The Agora was an area of political gatherings and commercial transactions, the locus of the administration and of justice, a religious and intellectual centre. The agora is already mentioned in Homer's epics, and represents, therefore, a constituent element of the ancient Greek city.

The Ancient Agora of Athens existed, in its known location under the North Slope of the Acropolis, already by the 6th century BC, and it continued to function as a public meeting area until the 3rd century AD. Its functions however have been substantially altered after the building of the Roman Agora and the Hadrian Library in its east side. In later years, the Ancient Agora continued to play in important role in the Athenian public life (possibly gymnasium), although it was already situated exta muros.

Close to the borders of the Ancient Agora, on the east side of the Panathenaic Way, laid the City Eleusinion, an important cult place, already in use during the Archaic period.

Northward of the Eleusinion the Plateia Odos (Wide road) linked the Ancient Agora to the new Roman one, into which have been moved almost all commercial activities. The Hadrian Library has been erected next to the Roman Agora during the 2nd century BC.