According to professor Simon Shibli, the head of Sheffield Hallam University's Sport Industry Research Centre, Olympics and World Cup are the two biggest sporting events in terms of interest and media coverage.
They both happen every 4 years and both involve nations from around the world competing. But questions like which has the best security and which is more popular on TV are still being debated.
This CBS Baltimore article claims it's a tie.
And to help you decide for yourself, Terra.com brought you a number-by-number comparisons of sports' biggest events.
Of interest, check out National Geographic's Top 10 Sporting Events.