Climbing up the walls used to be an expression of anxiety and frustration. Two decades into the extreme-sports era, its a description of what lots of people do with their free time. The ATLANTA ROCKS! location on Collier Road claims to be the largest indoor gym in the Southeast. With 12,000 square feet of climbing surface and climbing routes for beginners and experts alike, we have no reason to doubt them. It beats the hell out of spin class.