Rock City sits on top of Lookout Mountain on the Tennessee/Georgia border. It IS unique and it IS an extremely popular tourist attraction. Some people, however, may be a little disappointed. It depends on what you expect to find.
After seeing a never-ending stream of billboards touting its greatness, it's very easy to have some real high expectations.
Rock City is a walk through attraction that features unique rock formations that have been carved out of stone since the beginning of time.
It's a self-guided tour through 14 acres, so you can walk at your own pace. Some of the formations are interesting, like the 1,000 ton balanced rock and the needle's eye. Some are humorous, like Fat Man's Squeeze where you've got to suck in your tummy to get through. The swinging bridge, to me, was scary. You're suspended over this huge crevice on a rope and plank bridge that, naturally, swings every time someone moves.
I don't think it's something I would highly recommend. Again, it depends on what you're hoping to see.
One thing about Rock City that IS worth seeing, though, is the view from Lover's Leap. It's claim to fame is that you can see seven states. I don't think I could actually SEE seven states, but the overall panoramic beauty of the mountains is breathtaking.
Not a place for anyone afraid of heights.