Pilgrims came to Delphi from throughout the Greek world -- and much of the non-Greek world -- to ask Apollo's advice on affairs of state as well as small, personal matters. Unfortunately, the god's words were famously hard to interpret. "Invade and you will destroy a great empire," the oracle told Lydian King Croesus when he asked whether he should go to war with his Persian neighbors. Croesus invaded and destroyed a great empire: his own.
Delphi was also the site of the Pythian Games, the most famous festival in Greece after the Olympics. The Games commemorated Apollo's triumph over his oracular predecessor here, the snaky Python. Because Apollo was the god of music, the Pythian Games had more artistic contests than the Olympic Games. When you sit in the theater, you can imagine the flute and lyre contests and the dances and plays staged every 4 years throughout antiquity to honor Apollo.
Like so many ancient sites, Apollo's sanctuary at Delphi was first neglected, and then virtually forgotten during the Christian era. Kings and generals looted Delphi of its treasures; later, locals hacked up the buildings and used the blocks to build their own houses. The medieval and modern villages of Delphi sat atop the ancient site until the late 19th century, when the village began to be relocated just around the corner so that archaeologists could help Delphi reclaim its past.