Above the Pleistos Valley, on the slopes of Mt Parnassus, Delphi was once a mystical mecca, when the Sanctuary of Apollo attracted pilgrims who were fascinated by the oracle. The ruins of the ancient site, UNESCO World Heritage listed and one of Greece's top tourist attractions, cling to a slope below the red sandstone Phaedriades Rocks. Delphi makes an impression as much for its wealth of archaeological remains as for the beauty of the location.