Apollo's authority in the Greek world ran largely through Delphi. The Homeric Hymn to Apollo tells how the god founded the sanctuary by slaying the serpent Python at the site, a name that survives in Pythia, the title of his prophetess and in the Pythian Games. Seated over a cleft, the Pythia delivered responses that priests rendered into verse; over the temple were carved the maxims know thyself and nothing in excess, and beside it stood the omphalos, the stone marking what the Greeks called the navel of the earth.
Delphi was not a curiosity. Cities consulted it before founding colonies, changing laws or going to war; its answers shaped real decisions across the Mediterranean for the better part of a thousand years, and its ambiguity was proverbial, an oracle could be technically true and disastrously misread, as Herodotus delights in showing.
The other pole of his cult was Delos, the small island the same hymn names as his birthplace, where Leto, pursued by a jealous Hera, at last found ground willing to receive her. Delos became a Panhellenic sanctuary and, much later, the treasury of an Athenian empire that met under Apollo's protection.