Athens reckoned its year in twelve lunar months, Hekatombaion through Skirophorion, each one organised as much around the festivals it hosted as around the count of days. Hekatombaion, the first month, carried the Panathenaia, the city's central festival of Athena, held in an especially elaborate form every fourth year with athletic and musical competitions and a procession that carried a newly woven robe to the goddess's cult statue. Anthesteria, in late winter, marked the opening of the new wine and included rites addressed to the dead alongside its celebration, while Thesmophoria, kept by citizen women in honour of Demeter and excluding men from its central rites, structured the autumn.
The City Dionysia, in spring, was the occasion on which Athenian tragedy and comedy were performed, a fact that places the origin of Western theatre inside a civic religious festival rather than beside one. No other Greek polis shared this exact calendar. Sparta, Corinth, Delphi and every other Greek city-state kept its own months and its own festival cycle, so the Attic calendar is best understood as the most thoroughly documented example of a pattern repeated, with real variation, across the Greek world rather than as a panhellenic standard.