Police made the discovery on Monday in a network of ancient caves on the outskirts of the Rome.
Deep in the bowls of the ancient city's bedrock they found piles of old refrigerators, mattresses, sacks of old rubble, electronics and even dangerous industrial waste.
“It's terribly damaging, not only environmentally, but also for the city's archaeological heritage,” police commander Antonio Di Maggio told Rome daily, Il Messaggero.
“We found everything: tar, industrial waste, tyres, batteries...there's practically an underground lake of oil.”
After making the shocking discovery, police used drones to fully explore the network of bat-and-mice-infested tunnels to try to establish the extent of the dumping.
It is thought that local businesses and residents have been using the site to cheaply dispose of their unwanted goods for years. Police even discovered that unscrupulous dumpers had drilled shafts down into the caves from above, which they used as rubbish chutes to quickly dispose of their unwanted goods.
Police have now seized the caves and are working to identify to whom the rubbish belonged so that the litter louts can be prosecuted.
The network of caves stretches under the edge of the picturesque Torre del Fiscale park and runs under two ancient Roman highways: the Appian Way and Via Latina.
The remains of a Roman aqueduct at La Torre del Fiscale Park: Photo: Ufficio Stampa Tor Fiscale
Above ground, the peaceful area is home to the spectacular remains of luxury villas, aqueducts and ancient tombs.
“It's really sad. The Torre del Fiscale park is a jewel that has been recovered through many years of hard work from citizens,” a spokesperson for the park told The Local.
“The only part of the park that police sequestered was the entrance to the tunnels. We have actually been proposing to restore some of the tunnels for a while.”
But down below it's a different story.
A member of the police force gathers a jar of noxious muck.Photo: Polizia Roma Capitale
Story continues below…
Dangerous waste now litters the expansive caves and tunnels - which were quarried by slaves into the Eternal city's bedrock. The stone, known as Tufa, was a key ingredient in ancient Roman cement.
Once quarried, certain areas within the underground network became catacombs, places where some of the very first Christians of second and third century Rome once respectfully buried their dead.