¿What to do in Atlanta Airport?

I'm traveling from Mexico to Barcelona with an 8 hour scale on Atlanta, Georgia. Any recommendation? ¿Does anyone knows if it is possible to go out of the airport and return or if I have to stay there?
Thanks!

Use the link below to see what you can do. You can leave the airport, just make sure you are back in time and have your bording pass with you. Also allow enought time to clear security. you may have a long wait time depending on the time of day. Also Atlanta is known for delays.
I work for TSA

walk through all the terminals below..and avoid the train ..some of them feature art galleries from around the world while you are walking.

You can take the Marta train into the city from the airport. You can go see Olympic Square park, the Georgia Aquarium, or maybe go to CNN or the World of Coca-Cola.

Just make sure you get back on the train in time to make your connecting flight.

You'll have some time to leave the airport if you wish, but I don't recommend it. If your not familiar with Atlanta, then you should stay in the airport. Theres plenty of shops to see in the airport. You have several concourses to travel around. Check out this link for the airport to see what interests you.

Leave the airport at lease for a little while...8 hours is a lot of time

The Marta train passes right to and from the ATL airport (very convenient). You can catch it and visit some sights in ATL like the aquarium, the World of Coke, and the Underground. these are right in ATL downtown.