What’s the biggest event at the Olympic Games?

There’s a good case that it’s not running, or swimming, or gymnastics, but the celebration of nationhood. The opening ceremony to the 2008 Beijing Games was the most-watched event in television history. In the U.S. alone, tens of millions routinely tune in to the first night’s display. This year’s opening ceremony, beamed from Paris, the hometown of the modern Games’ founder Pierre de Coubertin, is likely to be no exception.

These parades are tremendous fun to watch. The ideal that animates them, however — that the Games belong in a single city to which athletes from across the world make pilgrimage — is looking increasingly threadbare. As the world’s demographic and economic center of gravity moves toward developing countries that will be experiencing choking summer heat by the middle of the next decade, it may become untenable.