Michael and Ted O’Neill made their discovery near lake Bracciano north of Rome while researching documentaries on ancient Roman aqueducts for MEON HDTV Productions. Here, beneath a dilapidated chapel dedicated to the Madonna on a pig farm near the town of Bracciano on the western shore of the lake, the father and son stumbled across the remains of a richly decorated nymphaeum, or shrine dedicated to water spirits, which they believe was built to mark the Caput Aquae of the Aqua Traiana, the penultimate of the 11 great aqueducts built by the Roman emperors to supply fresh water to the city. The discovery has since been confirmed by Professor Lorenzo Quilici of Bologna university, one of Italy’s leading experts on aqueducts, who has described it as “stupefying”.

The nymphaeum is flanked on either side by a basin, or reservoir, with a painted vault roof. The basins served to collect the water, filter it and then feed it into the stone channel of the aqueduct. This then collected water from other springs as it made its way around Lake Bracciano before heading south to enter the city on the Janiculum hill. Inaugurated by the emperor Trajan in 109 AD, the aqueduct was restored by Pope Paul V in the early 17th century, when it was modified to collect water directly from lake Bracciano and incorporated into the modern-day Acqua Paola.