At the bottom of the cella existed the adyton that was constituted by an above-section with a golden statue of Apollo and another underground in which Pythia - Apollo's priestess- went down in order to give the oracle. The underground section was divided once again in two spaces the "house" and the "antron". In the "house" were remaining the "theopropoi" that is to say those who asked for oracle and the priests, while in the "antron" entered only Pythia who was sitting in a tripod hearing the question of the "theopropoi", and coming in situation of ecstasy from the steams that emerged from a "gap of the ground ", from the laurel that chewed, from the water of Cassotis which she drunk, and from the faith that at this moment she came in communication with the god, she answered with inarticulate cries the question. The priests recorder the voices and gave the answer sometimes in metre speech and sometimes with common phrases.

There is interest to what happened before the prophecy: Pythia, the theopropoi and the priests had to be washed into the Castalia to be clear in soul and body since they will entered the sanctum. Theopropoi in order to take their oracle they were paying a sum of money and they sacrificed on the altar, a bull, a pig or a goat.

The animal should have been absolutely healthy and satisfying certain conditions otherwise was not given the oracle. The oracles were initially given only a time the by year's, in 7 the month Thargelion (day of birth of Apollo). Later they were given once a month, apart from the 3 of the winter, therefore they believed that Apollo was absent in the North, and in the sanctuary Dionysos dominated. Right in the oracle had firstly the residents of Delphi and those who had acquired an oracle after they had made big offers to the holy, as Chians did. The others waited for in line and the turn was determinated by lot.
If judging by the variety and richness of the offerings made to the temple, from the remote areas, and from the kings from where they came (Midas, Croesus, etc.) we can see how great was the power of the oracle in ancient times and how great was the role that played in relations between states and individuals in the society of the Greek city.
 

The worship of the god and the fame of the oracle expanded very fast, having the result in the 7th BC cent. to be implemented an already organised religious center known throughout the world, judging from the offerings devoted to it. At the same time, the Oracle contributed decisively to the large Greek colonization, since almost all of the metropolis (the cities that have sent settlers) consulted the god to the place of colonization, and the chances of success.

Big role in the shine of the sanctuary played also its connection with the amphictyony of Thessaly and Central Greece. That was one of the many associations, neighboring cities with public religious centre and common political objectives, and have been located around the Anthili at Thermopylae.

When however the automn meeting of the representatives of all cities was transferrred at the beginning of 6th c.BC to Delphi, they became the religious and political centre of the amphictyony.
This had two major consequences: a) The amphictyony acquired the direct control of the sanctuary and protected it by its enemies and b) due to the attractiveness of the temple, the amphictyony was quickly surpassed its local character, and became the pan-hellenic political centre playing the role of arbitrator in conflicts between cities - states of ancient Greece for several centuries.