The mile-long tunnel is believed to have been constructed in the fifth century but decades of inadequate maintenance mean that it is clogged with debris and silt, raising fears of blockages and collapses. An operation to clean and maintain the tunnel got under way last week and is expected to take two years.
Engineers will have to shift huge quantities of rubbish clogging up the tunnel, including plastic bags, tangled electric cables and other detritus.
The Cloaca Maxima was originally dug as a canal by the early inhabitants of Rome, but was subsequently covered over to become a subterranean sewer.
It was maintained throughout the Roman Empire and into the medieval era and was ultimately incorporated into the city’s modern sewerage system.
