Delphi was the site of the Delphic oracle, most important oracle in the classical Greek world, and it was a major site for the worship of the god Apollo. His sacred precinct in Delphi was a Panhellenic sanctuary, where every four years athletes from all over the Greek world competed in the Pythian Games.

Delphi was revered throughout the Greek world as the site of the omphalos stone, the center of the earth and the universe. In the inner hestia (”hearth”) of the Temple of Apollo, an eternal flame burned. After the battle of Plataea, the Greek cities extinguished their fires and brought new fire from the hearth of Greece, at Delphi; in the foundation stories of several Greek colonies, the founding colonists were first dedicated at Delphi.