In A.D. 79, Herculaneum, a small resort town on Italy's western coast, was buried, along with its larger neighbor Pompeii, under an avalanche of lava and ash by Mount Vesuvius. So deep were the towns buried that over the centuries even the memory of them faded. It was not until early in the eighteenth century that evidence of the towns was accidentally discovered. For the next fifty years, haphazard excavations and looting began to hint at the extent...