In Rome, they say there are due città–two cities, a modern one above ground, and an ancient another underneath. But this is a vast oversimplification.
Rome is a city of layers, of many different heights and depths. Ten to fifteen feet down are the remains of Late Antique Rome (between 1500 and 800 years old, roughly). And another fifteen feet below that is another. Recently, archeaologists have unearthed remains fifty or sixty feet below the current surface, but they have yet to determine the age of these finds.
Though the rule that old things get buried is more or less universal, the rate of sediment deposition in Rome is unusually high. There are two unique reasons for this–one political, and the other geographical.
According to noted archaeologist R. Bruce Hitchner, Roman officials have traditionally dealt with outdated buildings by demolishing them and literally smearing the remains on the plot of land. According to Hitchner, the debris for a two-story building added one to two feet in height, on which close-packed earth could be added to form a foundation for future buildings.
In an article for The Atlantic Monthly, novelist and historian Tom Mueller traces the origins of this trend. “After the Great Fire of A.D. 64 devastated two thirds of the city, [the Emperor] Nero spread the debris over the wreckage of republican Rome and then reshaped the city to his liking.”
While the Rome of today is relatively flat, it is not naturally so: it was originally a fairly hilly territory, which was useful for defense but became more and more inconvenient as the city’s population grew.
But the practice of spreading debris only explains the rapid jumps in city height during certain periods. It does not account for the steady layering that is observed throughout all districts of the city. Rome’s climate is responsible for this second layering pattern. According to Mueller, a solid inch of dust falls on Rome each year–consisting of tree leaves, pollution, sand, and powder from ruins. Though the rate of deposition is much slower in the parts of modern Rome that are in paved, in other locations “we are more than ten yards” farther from from Ancient Rome than were the first archaeologists who visited the ruins in the 16th century, Mueller writes.
Rome’s many layers makes it something of a Mecca for archaeologists.
“Something new is always being found here,” said Professor John Marino, who teaches the course Renaissance in Rome through ISA. “Even if you dig all 365 days, there is still more out there to be found.”