Mountaintop trail address: trailhead at AWARE Wildlife Center, 4158 Klondike Road, Lithonia, GA 30038
Visitors center address: 3787 Klondike Road, Lithonia, GA 30038
Cost of admission: Free
Acres: 2550
Approximate miles of trails: 11
Hours: Dawn to dusk
Miles from downtown Atlanta: 20
MARTA directions: Take the 86 from Kensington Station or the 116 from Indian Creek Station to the Mall Pkwy @ Klondike Rd stop. From there, walk west and then south along the PATH trail for about 2.5 miles to the visitors center, or exit the PATH trail earlier along one of the unpaved nature trails.
Parking: There is parking available at the mountaintop trailhead and visitors center (both addresses above) and at Vaughters' Farm (approximate address: 3366 Klondike Rd, Lithonia, GA 30038)
Trail surface: PATH trails are paved and boardwalk, other trails are unpaved
Blazes/markings: The trail blazes are documented on this map
Geocaching: There are many geocaches at Arabia Mountain
Best time to visit: The diamorpha bloom in March-April, and yellow daisies bloom in September
Guidebook mentions: Chapters 32-36 in Hiking Atlanta's Hidden Forests (1st edition), chapter 47 in 60 Hikes Within 60 Miles (3rd edition), chapter 60 in Hiking Georgia (4th edition)

Amenities:

Restrooms at mountaintop trailhead, visitors center, and Vaughters Farm (no running water)
Bike racks at Vaughters' Farm and the nature center
Picnic tables at nature center and other locations
Water fountain at Vaughters Farm

Links:
Arabia Mountain National Heritage Area website
Visitor guide
Trail map
NPS