Technicians walk the Acqua Vergine aqueduct, one of 11 Roman aqueducts that supply the fountains of Rome, including the Trevi Fountain. Speleologists are completing the first-ever mapping of the aqueducts that supplied ancient Rome and still run underground and along viaducts. (ANDREAS SOLARO/AFP/Getty Images)

Rome is dotted with thousands of fountains, many known for its historical and artistic significance. While tourists flock to these magnificent structures, including the famous Trevi Fountain, less is known about the vast network of hidden tunnels and aqueducts that run underground and feed these fountains. That is about to change.

This month, a group ofspeleologists are completing the on archaeology’s "final frontier," according to AFP. The mission of these specialists is to update the last above-ground map of the network compiled at the beginning of the 20th century by British Roman archaeologist Thomas Ashby.

Two thousand years ago, Roman engineers hacked out the aqueducts that brought fresh water to the city of Rome from solid rock. Today, speleologists are using the best of 21st-century technology. They are to map the dozen aqueducts that were built over centuries, measuring the size, elevation and direction of the tunnels, the Telegraph reported.

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A remote-controlled robot that has been named Lucius is also helping explore cisterns, drains and tunnels beneath the Roman Forum. The six-wheeled "archeo-robot", equipped with two powerful computers, three high-definition cameras and laser sensors, is able to walk along narrow passageways which are too small or dangerous for humans to enter.

Among the areas mapped by the group is the perfectly preserved on the grounds of a Franciscan convent in Vicovaro near Rome, according to the Daily Mail.The pick marks of the Roman diggers can still be seen in the limestone of the tunnel completed in 38 AD by the Emperor Claudius.

Rome's aqueducts are considered true feats of engineering.The Romans designed the aqueducts to use gravity to bring water from higher elevations to the empire's cities.

"Underground Rome is a final frontier," explorer Riccardo Paolucci . "Water was a fundamental service for hygiene. In a city like Rome, which had a million inhabitants, there were very few epidemics."

Only one of the aqueducts, the AcquaVergine, is still operational today. Itcan be accessed in various hidden locations near Rome including a doorway near the Villa Medici that leads down a spiral staircase to the water. The Acqua Vergine runs for a total of 20 kilometres and ends up in the Trevi Fountain.

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