Every four years a pan-Hellenic truce was announced and people from all over Hellas gathered at Olympia, in order to compete and attend the Games. The prize for the winner was the "kotinos", a garland made from wild olive tree.
Olympia was as sacred site as Delphi. The sacred precinct was situated in the valley of Alpheios, in the territory Pisatis and at the enclosure of Alte "the most beautiful place of Greece", in the north-western Peloponnese. 
Though the Games historically started at 776 BC, which is considered the first Olympiad, they were held from very ancient times and tradition tell us that they were renewed by Herakles.
In this unifying event, only free Greeks were allowed to take part. Greeks from as far as the gates of Herakles, the Caspian sea and Africa, came to compete and attend and philosophers, sages, heroes and well admired men could be seen here.
It is not accidental that Greece for the first time in history held the Games. This was a unique event, a product of a higher civilization, in which the people were honoring their race and Gods, who had favored them with arete, strength and grace.