The Archaeological Site of Delphi has been recognized as a UNESCO World Heritage Site since 1987 and it is an internationally famous Panhellenic sanctuary. It is related to many key events in Greek history and it had a significant impact on the progress of culture and civilization. Remains of a Mycenaean settlement and a cemetery were found within the boundaries of the sanctuary. More specifically, until the 8th century BC, the traces of a dwelling were few and sparse. With the beginning of Apollo's worship, the sanctuary and the oracle started to develop. The period from the 6th to the 4th century BC played a very important role in establishing or consolidating the reputation of the Delphic Oracle. Entire cities, rulers, warriors and common people rushed to the site to consult the god. They expressed their gratitude with brilliant vultures which gradually filled up the sanctuary. God Apollo gave the oracles through Pythia, the famous priestess, whose identity was one of the biggest mysteries in ancient Greece. During the period of the Roman rule after 168 BC, Delphi was sometimes favored and sometimes plundered by the emperors. In 394 AD, with the predominance of Christianity, the operation of the oracle was ended. The order to end it was given by the emperor Theodosius the Great. As a result, the sanctuary was gradually covered up by soil and rocks, while much later a village, Castri, was settled above it. In 1891, the French archaeological school got approval from the Greek government to carry out systematic research and excavations after first removing the village of Castri.