Pythian * Isthmian * Nemean * Olympic
The Pythian Games were held in honour of Apollo at Delphi; the Isthmian Games, at Corinth for Poseidon; the Nemean Games, at Nemea in honour of Zeus. But the most famous in the ancient world were the Olympic Games, held in honor of Zeus at Olympia in the Peloponnese, which attracted city states from across the Greek (and later Roman) world.
Each of these PanHellenic Games were held at intervals of either two or four years and were arranged so that each year there was at least one competition open to any free-born Greek. The first recorded winner is from 776 BC though the practice was considerably more ancient. The Games seem to have been designed to select the very best in order that they could offer up a sacrifice that would be the most pleasing to the Gods. This also explains the sacred truce, the cult of heroic nudity, the simple garlands awarded to the victors and the decision of the Christian emperor Theodosius to close down the games in 394 BC.
Excerpted from: Rogerson, Barnaby. Rogerson’s Book of Numbers: The Culture of Numbers–from 1,001 Nights to the Seven Wonders of the World. New York: Picador, 2013.