Olympia
The sanctuary of Zeus in the western Peloponnese and home of the Olympic games. Greeks counted years by Olympiads, the four-year periods between the games, from 776 BCE.
Today: Olympia, Elis, Greece
How the Romans fixed the year
Censorinus, On the Birthday 20–22 (238 CE), in the edition of Friedrich Hultsch (Leipzig, 1867) · 238 CE
secundum quam rationem nisi fallor hic annus, cuius velut index et titulus quidam est V. C. Pii et Pontiani consulatus, ab olympiade prima millensimus est et quartus decimus, ex diebus dumtaxat aestivis, quibus agon Olympicus celebratur; a Roma autem condita nongentensimus nonagensimus primus, et quidem ex Parilibus, unde urbis anni numerantur;
By this reckoning [of Varro's], unless I am mistaken, the present year is the 1,014th since the first Olympiad. This year is marked and named, as it were, by the consulship of those most distinguished men, Pius and Pontianus. Its Olympic count starts from the summer days when the Olympic games are held. It is the 991st year since Rome was founded, counting from the Parilia, the festival from which the city's years are counted.