The 28th Summer Olympics have gotten under way in Athens, amid the tightest security in the history of the Games.

The start of the opening ceremony on Friday marked the return of the Games to Greece, where they were born and then revived. The Olympic torch arrived in Athens Wednesday after traveling across five continents. Tens of thousands of people cheered, as athletes from 202 delegations paraded into the new Olympic Stadium.

The start of the opening ceremonies came as Greeks confronted the news that two of the country's top sprinters face doping allegations. Kostas Kenteris and Ekaterini Thanou failed to appear for a doping test this week. Olympic officials have delayed a formal hearing into their absence until Monday.