The famous ancient city known for its ruins in Greece is Delphi. Located on the slopes of Mount Parnassus, Delphi was considered the center of the world by the ancient Greeks and was home to the Oracle of Delphi. This significant religious site attracted visitors from all over Greece who came to seek guidance from the oracle, believed to provide prophecies inspired by the god Apollo. The ruins include the Temple of Apollo, a theater, and various other structures. Today, Delphi is a UNESCO World Heritage Site and continues to captivate visitors with its rich history and stunning scenery.