~ Legendary Rome ~
- 4 -

The Mysterious Fons Olei



Trastevere is probably Rome's most typical district, where old houses and narrow streets remind us what the whole city must have looked like centuries ago.
The heart of the neighborhood is a charming square, piazza Santa Maria in Trastevere, which is the name of the ancient church that stands on one side, faced by the fountain that stands in the centre. Curiously, the church is considered the earliest of its kind, having been likely the very first one founded in Rome, in the first quarter of the 3rd century AD, although the original building underwent several alterations over the centuries. Also the fountain is credited as the oldest one still working among the extant ones, having been first built in the late Middle Ages; however, the original one stood in a less central spot of the square, and was rebuilt several times, until in the 1800s it took its present shape.

piazza Santa Maria in Trastevere
The church is famous for its well preserved mosaics, many of which by Pietro Cavallini (late 13th - early 14th century), who also restored the older ones in the upper part of the fašade.

an old wood-print of the square;
the early fountain is on a less central spot
But there is a less known anecdote about the church, concerning a curious phenomenon which, according to tradition, is said to have taken place here 2,000 years ago.
In those days, this was the site of a hospice for retired soldiers, called Taberna Meritoria. Here, one day in 38 BC, a gush of oil suddenly spouted from the ground. This mysterious event was given the Latin name fons olei ("oil source", or "oil fountain"): a record of this prodigy is still found in some old chronicles, which tell us how the oil "for the time length of one day and one night, like a broad river reached the banks of the Tiber".


Over the years, Roman augures (official foretellers) as well as ordinary people gave this event all sorts of magical and religious meanings. According to the early Christian version, this prodigy may have foretold Christ's birth. Apparently, this was the reason that around AD 325 led Christians, whose number was gradually increasing, to ask the Roman emperor Alexander Severus (3rd century) to let them have the old Taberna, and later built on this site the very first church.

the church (partly hidden) and the fountain in a detail of a map of Rome (1472), with the caption: →
Santa Maria in Trastevere from where the oil ran towards the Tiber on the night of the Lord's birth

There is enough evidence that that a Roman building did actually stand on this site; two small but rather interesting ancient mosaics are on display in the church's sacristy.


one of the two Roman mosaics in the church
According to a more rational theory, instead, the expression fons olei may have a different origin.
The first emperor, Octavian Augustus (27 BC-AD 14), used to enjoy naumachiae, i.e. mock naval battles, for which real ships were used: they were held in actual stadiums built for this purpose, and filled with water on the occasion of such events. The memory of this peculiar form of entertainment was still lingering in Rome in the 16th century, when piazza Navona used to be flooded during the summer weekends (see the Rioni section).

a reconstruction of the naumachia
in Trastevere, from a map of
ancient Rome by Pirro Ligorio (1561)

Octavian Augustus' naumachia stood in Trastevere. In order to fill the arena, a new aqueduct called Aqua Alsietina was built; the water it carried, collected from the Lake of Martignano, north of Rome, was non-drinkable, and was partly used also for irrigating the nearby Gardens of Caesar. The aqueduct stopped working in the 4th century, when the surface of the lake dropped below the level of the aqueduct's tunnel.
Any fountain that drew such water may have been called in Latin fons olidus ("dirty fountain" or "polluted fountain").
Therefore, fons olei might simply be a corruption of the expression fons olidus.


Christ's Birth, by Pietro Cavallini (late 13th century)
with a detail of the Taberna Meritoria
But for those who like to believe in the legendary version of the story, just below the altar in Santa Maria in Trastevere's church, on the very spot where the oil is said to have gushed out, an inscription remembers the event. And among the famous mosaics in the apse featuring biblical stories, the panel with Christ's birth clearly shows the old Taberna Meritoria, and a stream of oil reaching the Tiber.


the spot where the fons olei is said to have sprung from the ground