The Panathenaea was an annual festival in Athens; every four years there was an especially elaborate festival which had international appeal. The prizes were amphorae of olive oil – which held considerable monetary value both because of the oil and the quality of the vases (the Athenians did a thriving trade in ‘fake’ Panatheniac vases, such was the appeal of the design). This was not a crown game, as the victors did win prizes with monetary value. Its importance fell and rose with the importance of Athens as a power: under Roman rule it seems to have precipitously declined in importance.
A very old, but still useful encyclopedia entry on the festival. However, only take this as a summary of information and not as an academic source or solid reference.
Excellent collection of primary sources on the Panathenaea.