The Georgia Perimeter College Decatur Campus is at 3251 Panthersville Road closest to the Decatur MARTA Station on the blue rail line. Transfer at the station to bus 15 or transfer to bus 34 at the East Lake MARTA station, also on the blue line. The college is near the end of the line on both bus routes.
If your starting location is on the red or gold line, transfer at Five Points to an eastbound Indian Creek train to reach the East Lake and Decatur stations.
To get specific MARTA directions and schedules from your starting location, use Google Maps.