an ancient Greek city on the slopes of Mount Parnassus; site of the oracle of Delphi
"The priestess at the sacred site on the slopes of Mount Parnassus spoke through a crack in the ground to deliver prophecies from Apollo."
A city of ancient Greece, the site of the Delphic oracle
"The travelers journeyed to Delphi, the sacred city in ancient Greece where the famous oracle once resided."
The word delphi comes directly from Ancient Greek and refers to the famous site of Apollo's oracle. It entered English as a proper noun without changing its original meaning.