A maritime Pompeii

The San Rossore train station on the edge of Pisa, Italy, is a lonely stop. Tourists who visit this city to see its famous leaning tower generally use the central station across town. But San Rossore is about to be recognized as one of the country's most significant archaeological digs. For nearly a decade archaeologists have been working near and under the tracks to unearth what is nothing short of a maritime Pompeii.

So far the excavation has turned up 39 ancient shipwrecks buried under nine centuries of silt, which preserved extraordinary artifacts. The copper nails and ancient wood are still intact, and in many cases cargo is still sealed in the original terra cotta amphorae, the jars used for shipment in the ancient world. They have also found a cask of the ancient Roman fish condiment known as garum and many mariners' skeletons—one crushed under the weight of a capsized ship. One ship carried scores of pork shoulder hams; another carried a live lion, likely en route from Africa to the gladiator fights in Rome.

What's most dramatic about the discovery of this maritime graveyard is that the ships date from different centuries both before and after the advent of the Christian era, meaning the shipwrecks did not happen simultaneously but over time in the same area. Researchers say that starting around the 6th century B.C. the cargo docks of the port of Pisa were accessed by a canal that made a loop connecting the harbor to the open sea. Every hundred years or so over the course of nearly a thousand years, tsunami-like waves violently flooded the waterway and capsized and buried ships, their cargo and their passengers and crew, alongside uprooted trees and even tiny birds and animals. The 39 shipwrecks, of which 16 have been age-dated and partially or fully excavated so far, date from around the fifth century B.C. to the fourth century A.D.