This month's edition of Smithsonian Magazine is excellent:
In the Field Museum exhibition, some of those moments are brought eerily to life by plaster casts of Pompeii and Herculaneum’s residents at the moment the eruption overtook them. The doomed couple fleeing down an alley with their two daughters (if they were indeed a family; some have suggested the man was a slave) were the first Vesuvius victims to be so revealed, although these early casts are not in the exhibition. In 1863, an ingenious Italian archaeologist named Giuseppe Fiorelli noticed four cavities in the hardened layer of once-powdery ash that covered Pompeii to a depth of ten feet. By filling the holes with plaster, he created disturbingly lifelike casts of this long-departed Pompeiian family in its final horrifying moments. It was as though an eyewitness from antiquity had stepped forward with photographs of the disaster.The exhibit is at the Field Museum in Chicago through March 26.