About 300 meters southeast of Campofilone stands an intriguing underground Roman structure made of pozzolanic concrete, consisting of two large rectangular chambers covered by barrel vaults. Over 12 meters long and divided into four sections, the building features square openings at the top once used for ventilation and inspection.
The original function of the structure remains uncertain: according to some scholars, including Giovanni Ciarrocchi, it was a water cistern designed for the collection and purification of rainwater. Others, however, believe it served as an underground granary, given the complete absence of limestone deposits and the notably dry condition of the interior.
Over the centuries, the structure may also have served a defensive or sheltering purpose: its concealed position and narrow openings would have provided refuge and protection for the local population during Saracen raids along the coast.
