Δελφοί – Delphi
The Oracle at Delphi was the most important oracle in the classical Greek world, and a major site for the worship of the god Apollo. People consulted the the sibyl or priestess of the oracle on everything from important matters of public policy to personal affairs. It was also there that every four years, from the 6th century BC, athletes from all over the Greek world competed in the Pythian Games, one of the precursors of the Olympic Games.