This is Delphi and it was the greatest Oracle of the antiquity.
Walking through the “Sacred Way” that leads to the Temple of Apollo, you will pass by the treasury of the Athenians, where they used to host their valuable offerings in tribute to god Apollo. Continuing your way up to the slope of the mountain, you will see the Ancient Theatre and further above the stadium where the Pythian Games were hosted.
Below these areas, are the temple of Athena Pronoia, the Gymnasium as well as the Castalia Spring.
Your experience will be completed after visiting the archeological museum of Delphi and have lunch at a local restaurant.
On the way back to Athens, you can spend some time at the picturesque town of Arachova and and visit the very well-preserved middle Byzantine period Monastery of Hosios Lucas, which is included on the UNESCO'S World Heritage List.