The Panathenaea was the most important of all the festivals at Athens: it was in honour of Athena herself. Tradition had it that the festival had been inaugurated by the mythical king Erichthonius. When the agricultural communities of Attica were 'synoecized' with Athens, the festival was reorganized; was given the name Panathenaea; and was kept on the twenty-eighth of Hekatombaion (July).
Starting in 566/5 B.C. (the archonship of Hippoclides), the Great Panathenaea was instituted: this was celebrated every four years, with conspicuous brilliance, it lasted twelve days, and there were many rites and sacrifices. The most prominent of these was the so-called hecatomb. There were also competitions, open to all Hellenes, in music and athletics. The sacrificed meat was distributed to the citizens in the Agora area. Another competition included in the Great Panathenaea was for the pyrrich dance: armed men, from every age group, took part in this.
The night before the Great Panathenaea, there was a vigil, with dancing by young men and girls. At sunrise on the twenty-eighth of Hekatombaion - Athena's birth day - the torch-race started. The object was to bring the new fire from the grove of Academus, beyond the city walls, to the altar of Athena on the Acropolis. There followed a grand procession, in which the whole citizen population took part. Its starting-point was the Kerameikos; its finishing-point was the Acropolis; and its purpose was to transfer offerings to Athena, principally the sacred peplos destined to clothe the wooden image of Athena Polias.
The peplos was a huge rectangular textile showing the Gigantomachy ('Battle of Gods and Giants'). It was woven every year by women of Athens - the so-called ergastinai under the supervision of the woman priest of the god. This was the same subject that appeared on the pediment of the temple of Athena on the Acropolis in Pisistratus' time. It was linked with the myth of the distinguished part played by Athena in the Battle of the Gods and the Giants. The textile was unfurled like a sail on a ship-on-wheels. The ship made its way through the Agora. When it reached the Areopagus hill, the peplos was taken down and carried onward by hand, to be entrusted to the male priests who had the task of wrapping it round the god's likeness. Those who took part in the procession were women (kanephoroi) with baskets of offerings for the god; elderly men (thallophoroi) holding branches of olive; young male riders and other males (skaphephoroi) with vessels called skaphai; and women or young girls (hydriaphoroi) carrying a water-jug on the shoulder. The donation and transport of these vessels was a metic privilege. In the procession there were also Athena's sacrificial animals - she-goats, rams, bulls, cows, and sheep. It is the procession of the Great Panathenaea which has been seen by most scholars as the scene portrayed on the Parthenon frieze.
Many competitions were laid on for the festival, with athletes from other city-states taking part. The winner received as prize a Panathenaic amphora filled with olive oil, and was crowned with a branch of olive. Moreover, starting in 425 B.C., cities that were in some sense dependencies of Athens - Athenian colonies, for instance, or allied towns - sent their representatives to Athens with sacrificial animals and votive offerings.
The Great Panathenaea has justly been described as Athens' most important festival. It was not simply a display of the Athenian hegemony's strength and superiority, it was a symbol of the city's unity by virtue of the participation in it of the whole Athenian population.
Source: Culture Athens