The priesthood of Athena Polias, guardian of the goddess's ancient wooden image on the Athenian Acropolis, was not an office anyone in Athens could seek. It belonged by inherited right to the genos Eteoboutadai, one of the old aristocratic clans that supplied particular priesthoods generation after generation, and it was held for life rather than for a fixed term, unlike most Athenian religious offices, which rotated annually or by lot. A woman appointed to it, typically while still young, could expect to hold the single most senior religious position open to any Athenian woman for the rest of her active life.
Lysimache held it for sixty-four years, a tenure so unusual that Athens itself marked it: a statue base found on the Acropolis, inscribed IG II^2 3453, records the length of her service directly, and the elder Pliny, writing centuries later in Rome, still knew of a portrait statue of her, sculpted by Demetrios of Alopeke, whom Pliny credits with pursuing likeness over idealization in his portraiture. That her tenure was commemorated twice, once by Athens in stone and once by a Roman encyclopedist drawing on Greek art-historical tradition, is itself a measure of how exceptional sixty-four unbroken years in the office was thought to be.
Her years in the priesthood spanned the most consequential decades of classical Athens, from the buildup to the Peloponnesian War through its most difficult years. As the city's senior priestess of its patron goddess throughout that period, Lysimache would have presided over the Panathenaic rituals, the annual offering of the new peplos to the ancient image, and the religious business of a city fighting for its survival, an institutional continuity running underneath decades of political and military upheaval.