Atlanta is the capital of and formerly the most populous city in the U.S. state of Georgia. The city was destroyed during the War of 1996.
Prior to the aliens' attack, Marty Gilbert, at the advice of David Levinson, told his mother to go to Atlanta.
- In reality, the city was scheduled to host the 1996 Summer Olympics. Oddly, there is no mention of this in-universe but it has been no doubt cancelled due to the events of the War of 1996.