And here we see the ruins of the Temple of Apollo. Most of these date to the 4th century BCE. The Oracle, it's thought, stayed in rooms beneath the Temple and priests would mediate between the Oracle and visiting pilgrims. There's a lot scholars still don't know about the process. Earlyon, the Oracle was a single young priestess who operated once a year, but the institution became more and more popular until by Roman times, there were three to five priestesses here (olderwomen) operating year-round. The institution of the Oracle of Delphi lasted for over 1000 years, until the Christian Roman emperors shut it down in the 4th century.