Delphi is an ancient site in Greece and a modern town, which was an important part of various stories in Greek mythology. Ancient Greeks believed that Delphi was the centre of Grandmother Earth which Zeus was trying to find. Towards this end, the king of gods let two eagles fly in opposite directions from the top of Mount Olympus. The two eagles eventually crossed paths in Delphi, which is how the omphalos (navel) of the Earth was considered to be there.
The Oracle of Delphi, or Pythia, was famous throughout ancient Greece, and people from all the then-known world would flock to the area seeking advice. The Oracle served the god Apollo, after he had slain Python, the dragon who protected the navel of the Earth. As a tribute to Apollo, the Pythian Games were held every four years, and were the precursor of the Olympic Games.