The Oracle of Delphi was the oldest of the four Oracles controlled by Apollo. The only Oracle older was the Grove of Dodona (which was controlled by Rhea). The Oracle of Delphi was not only a location but also a person. Those who sought the future would go to Delphi and ask the Oracle a question and would recieve an answer in the form of a prophecy. The prophecies were in verse and would be riddles of sorts which would have to be interpretteed. The new Oracle of Delphi is located in Camp Half-Blood.