A weekend getaway to Macon will bring out your inner history buff ajc.com - get the latest breaking news, showbiz & celebrity photos, sport news & rumours, viral videos and top stories from ajc.com Daily Mail and Mail on Sunday newspapers.
While the land and underground passageways of Mammoth Cave National Park are now traversed by tourists, guides and the occasional bat, millions of years ago the region was more popular
Here are photos - old and recent - of the gypsum mine of Grand Rapids, Michigan (recently, a sinkhole developed, revealing a portion of the gypsum mine).