ELBERTON, Ga. -- Driving north from Atlanta on I-85 toward South Carolina, you exit east at Georgia Highway 51, then exit again at Highway 17, which takes you straight to the city of Elberton. Once in Elberton, population 5,000, you take Highway 77 north for almost nine miles. Eyes scanning the horizon, you finally see it perched on a high knoll, with an easy-to-miss turnoff onto a small road that leads practically up to its foot. It stands alone in all its mighty glory, and on any given day you’ll likely be the only visitor. Four rectangular slabs of granite...