Stone Mountain is located just east of Atlanta and is reached via US Highway 78 East. This highway starts at the I-285 Perimeter Highway on the east side of Atlanta and goes to Stone Mountain and beyond.
Take I-285 to the east side of Atlanta and take exit 39B onto Highway 78 eastbound. Drive east on Highway 78 for about seven miles and take exit 8 to the East Gate.
To reach the west gate, drive east on Highway 78 for about five miles from I-285. Take exit 5 to Georgia Highway 10 West. Drive southwest on Highway 10 for 1.1 miles and then turn left onto James B. Rivers Memorial Drive (sign says JBR Memorial Drive). Drive east for about 1.3 miles and you will reach the West Gate.
The Maps section of the app contains a driving map that illustrates these directions.