Researchers have mapped an entire Roman city using advanced ground-penetrating radar (GPR) technology in what they describe as an archaeological first.

A team from Ghent University in Belgium and the University of Cambridge in the U.K. conducted the first high-resolution GPR survey of a complete Roman settlement—Falerii Novi, located just over 30 miles of Rome in what is now the region of Lazio in Italy.

The technique the researchers used revealed the entire layout of the city—which remains deep underground—as well as a bath complex, a market, a temple, an impressive public monument, and even a large system of water pipes, without the need for any excavations, according to a study published in the journal Antiquity.

The researchers say that advanced GPR surveys such as this could "revolutionize" archaeological studies of ancient urban sites, especially those that cannot be excavated because they are too big, or lie beneath modern structures and settlements.