The Areopagus or Areios Pagos is the "Rock of Ares", located north-west of the Acropolis Hill.
This hill is where court took session in the ancient times for the trial of murders.
Today, it is nothing more than a wonderful archaeological sight for visitors that give the best background of the Acropolis for especially nice photographs.
HOW TO GET THERE
BY FOOT: From Agion Asomaton Square and the Thissio Metro Station, follow the Apostolou Pavlou Walkway for over 1 km to find on your right hand side the Areopagus Hill.