ROME (Reuters Life!) - Two British film-makers believe they have solved a mystery that has foxed archaeologists for centuries: the source of a 1,900-year-old aqueduct which supplied the ancient city of Rome and even the early Vatican.
The father and son team of Edward and Michael O'Neill uncovered the series of tunnels and reservoirs beneath an abandoned chapel near Bracciano lake, 26 miles north of Rome, while making a documentary on Roman aqueducts.
They believe the aquifer was the main source for the Aqua Traiana, a massive aqueduct built by the Emperor Trajan in 109 AD, which powered the flour mills of ancient Rome and supplied the area near the Tiber where St. Peter's Basilica was built in the fourth century.
"The water from this site would have supplied the early Vatican and would have been used to baptize some of the first Christians," Edward O'Neill told Reuters.
The aquifer, which now forms part of a pig farm, had long been believed to date to Medieval times. But after uncovering a 17th century document in the Vatican archives relating to the site, the O'Neills came to believe it was much older.
Using long iron ladders to descend into the belly of the water system, the O'Neills quickly identified the characteristic diamond-patterned brickwork, known as "opus reticulatum," used by Roman engineers.
The find was corroborated by Lorenzo Quilici of Bologna University, an expert on ancient aqueducts. He identified the reservoir complex and the Madonna of the Flower chapel above it as forming part of a massive ancient nymphaeum -- a temple dedicated to the water deities of classical mythology.
The Aqua Traiana was one of Rome's 11 great aqueducts, part of a network believed to measure some 500 km (310.7 miles). It took its water from springs around the volcanic Lake Bracciano and headed south, entering Rome on the western Janiculum Hill, where it powered flour mills to make Rome's bread. The giant aqueduct fell into disuse in Medieval times but was revived by Paul V in 1612 to supply the area around the burgeoning Vatican. He renamed it the Acqua Paola.
Paul, however, was unable to use the water from the hydraulic complex between the Madonna of the Flower chapel because it had been taken by a local duke, as the document in the Vatican archives shows.
So the Pope ordered the aqueduct to be supplemented with waters taken directly from the lake, which were of a lower quality.
"To this day, if something is not very good, Romans will say it's as good as the water of the Acqua Paola," said O'Neill, who hopes to raise funding for a thorough archaeological excavation of the site.
Editing by Paul Casciato