The answer to the question is "THE FIRST OLYMPIC GAMES"
I can't see "this" calendar.
Ancient Greek myths did not keep a calendar.
Ancient Greek myths did not use a calendar so no one knows.
The basis for a calendar.
alpha
There was an ancient Egyptian calendar, but modern Egypt uses the Coptic Calendar, which is based on the calendar of ancient Egypt.
The third month of the current calendar [March] is named after the ancient Greek Olympian god Ares [latin Mars] - the warrior god, civil order and courage.
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It means:agrammatos
They were the religion of the ancient Greeks.
a long time ago
It is an ancient Greek analogue computer and orrery used to predict astronomical positions and eclipses for calendar and astrological purposes.