Hartsfield-Jackson Atlanta International Airport (ATL) is not just big; it is consistently one of the busiest and most sprawling airports in the world. In 2026, it remains a primary global hub, serving over 100 million passengers annually. The airport complex covers nearly 4,700 acres and features two massive terminals (Domestic and International) connected by an underground "Plane Train" and a pedestrian walkway that spans seven concourses (T, A, B, C, D, E, and F). To put its size in perspective, the walk from the start of Concourse T to the end of Concourse F is over a mile long. Despite its massive scale, ATL is remarkably efficient, with the Plane Train arriving every two minutes to ferry passengers between gates. If you have a connection in Atlanta, a "small" layover of 45 minutes can be quite stressful because of the distance between concourses, so most experienced travelers recommend at least 90 minutes to account for the sheer physical size of the facility and the volume of people moving through it.