Which airport is the busiest in the world?

The biggest airport is not necessarily the busiest one. If you were to measure all the airports around the world, the King Khalid International Airport in Riyadh, Saudi Arabia, would be the largest: It takes up some 81 square miles (209 square kilometers), an area larger than many cities! But the Hartsfield-Jackson Atlanta International Airport is the busiest airport in the world, handling nearly 95.5 millions passengers annually in 2012. Next on the list are Beijing Capital International Airport (81.9 million); London Heathrow Airport (70 million); Tokyo International Airport (66.8 million); and Chicago's O'Hare International Airport (66.6 million).