The sanctuary dedicated to Athena Pronaia was erected down the hill and southeast of the Sanctuary of Apollo in an area known as Marmaria. The temple is in the style of a tholos built in the 4th century BCE, it has been identified as the work of the architect Theodoros of Phokaia. According to Herodotus sometime in the 4th century BCE, the temple was destroyed when barbarians ascended on the sanctuary to plunder Delphi. In his account, "The Barbarians had just reached in their advance the chapel of Minerva Pronaia, when a storm of thunder burst suddenly over their heads- at the same time two crags split off from Mount Parnassus, and rolled down upon them with a loud noise- crushing vast numbers of them beneath their weight- while from the temple of Minerva there went up the war-cry and the shout of victory" (Hdt., 440 B.C.E., Book VIII).
By this time, the oracle was still acting independently and was not yet under any kind of control by the state. There is significant evidence of people primarily from mainland Greece, but also from Crete and Cyprus, making pilgrimages to Delphi to worship and seek advice from the gods via the oracle. Pilgrims, as well as state authorities, were required to pay in order to seek council from the oracle, so consequently Delphi, still called Pytho at the time, accumulated an enormous wealth. It was common for wealthy aristocrats and military leaders to give great sacrifices on the Altar of Apollo to appease the gods or to thank them for the generosity they bestowed. "After this Croesus, having resolved to propriate the Delphic god with a magnificent sacrifice, offered up three thousand of every kind of sacrificial beast, and besides made a huge pile, and placed upon it couches coated with silver and with gold, and golden goblets, and robes and vests of purple; all which he burnt in the hope of thereby making himself more secure in the favor of the god" (Hdt., 440 B.C.E., Book I). Undoubtedly the attention of powerful city-states was drawn to Delphi, now a powerful entity in itself. The ambiguity of the priest's interpretations of the oracle's intoxicated ravings was largely responsible for the continued support by the city-states. Politically, the priests of Delphi became very powerful. They acquired the ability to bend the will of those with military and political power, especially because it was through them that the oracle's messages were understood.
The first Temple of Apollo, built in the second half of the 7th century, was destroyed by a fire in 548 BCE and according to Herodotus reconstruction was not underway until 513 BCE. In 373 AD, the temple was destroyed again by an earthquake and rebuilt in much the same manner as the old. During this time there was an abundance of treasuries erected to hold the vast wealth still accumulating, the first one built by Kypselus of Corinth. They took a box-like shape, similar to that seen at Olympia, but with an Ionic order instead of Doric. Among the treasuries, there were also other dedications such as the two kouroi given by the Argives and the marble sphinx placed on top of a marble column and capitol given by the Naxians.
As Christianity was spread in the beginning of the first century AD, Delphi became less important. By the edict of Theodosius the Great in 393/394 the end of Delphi was official. The edict outlawed the practice of ancient religion and the Panhellenic games. By the 5th century AD, a Christian community resided there, erected churches and defaced the ancient marble temples with embossed Christian crosses. Three known Christian basilicas were built in the area, and in 620 AD the area was most likely completely abandoned due to Slav invasions.