Delphi is an archaeological site and a modern town in Greece. Delphi was the site of the Delphic oracle, the 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 Pan-Hellenic 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 oversized cone-shaped thing), the centre of the earth and the universe.
– Justin