Delphi was not chosen randomly in antiquity for the construction of the temple and the oracle of Apollo, neither for its attribute as “navel of the earth”. The location has an amazing dynamic created by the strong energy flow, the naturally fortified spot with a unique view to the gulf of Itea along with the rich vegetation, sources which sprang from the rocks and a strategic location on the mountainous routes which connected eastern and western Mainland Greece.  

It is possible that in this region pre-existed a sanctuary dedicated to Gaea (Earth), due to the gaps on the ground, from where emanated gas; upon coming in contact with this gas one fell in trance. According to mythology, this ancient oracle was guarded by an enormous serpent called Python. The god Apollo managed to kill the chthonic beast and to control the oracle. However, it is possible that this “prehistory” of the area is a later mythological construction. 
In the Iliad the oracle is already mentioned as rich and powerful. It seems that it reached its peak at the end of the archaic and the beginning of the classical period, when the temple of Apollo was erected along with the oracle and the oracle archive it housed. In the same period were also built  most of the treasuries of the Greek cities, where ex-votos were kept, precious either as artifacts or for their significance for the collective memory of the citizens (booty of battles etc). The oracle was related to two important aspects of Greek history: the colonization and the Amphictyony. According to tradition, the Greek cities asked the oracle of Delphi to suggest a location for the establishment of their colonies. On the other hand, after the First Sacred War, Delphi became the seat of the Amphictyony (the religious confederation of Central Greece), a fact which sealed its later history. It was roughly in that period that the Pythian Games were permanently established, namely sacred athletic contests in honour of Pythian Apollo, which acquired a panhellenic status as well as a prestige similar to that of the Olympic games. 
The evolution of Delphi within the ancient world, therefore, is not accidental and thus the declaration of the present archaeological site as a World Heritage Monument was not done randomly. The enhancement of the architectural complex through systematic excavations at the end of the 19th century and during the first half of the 20th century, the danger it faces due to the steep inclination of the ground and the constant landslides and particularly the importance of Delphi as an oracle, a centre of political and cultural evolution, as a panhellenic sanctuary and a place where panhellenic games were organized made the preservation of its history and of its archaeological remains as well as of the values which emerged through it an absolute necessity. 
The most important of these values are summarized in the so-called Delphic maxims, inscribed in the vestibule of the temple; these proverbial sayings came to symbolize Greek thought, spreading to the extremities of the Greek World, particularly during its expansion in the Hellenistic period.