It's check-in time for today's Geo Quiz. We're coming up on the busiest time of year for American travel -- especially air travel.

Atlanta's international airport is used to coping with the traffic. It's one of the world's busiest.

Atlanta served 89 million passengers last year, according to the industry tracker Airports Council International.

That number includes both domestic and international travelers. But we want to focus on JUST the international fliers.

With that in mind, can you name the five busiest airports in the world. Think of these 5 airports as major intersections where more people come and go - than stay.

We'll settle for the names of the airports or the cities where they're located...