Subterranean Siena

By Roderick Conway Morris

SIENA 1 March 1997

Comune di Siena
Section of Siena's Subterranean Bottini

Siena has one of the most perfectly preserved medieval cityscapes in the world. But regular visitors who may think they know the town pretty well, and even the Senese themselves, are just beginning to discover that below the city's steep hills and winding streets, there lies an extraordinary network of hidden thoroughfares: the 'bottini', over fifteen miles of medieval tunnels that still feed Siena's public fountains, and until recently provided the only supply of running water.

The layout of the 'bottini' was a closely-guarded state secret throughout the Sienese Republic's long struggles against its neighbors - Florence being its arch enemy. The system was never accessible to any but a handful of specialists and workmen, and the age-old traditions of silence about their very existence were carefully maintained by successive 'bottinieri', the engineers charged with their construction and upkeep, until just a few years ago. Now, for the first time, the city's Comune (Municipality) is allowing a limited number of visitors to take walks through them.

The term 'bottini' - the name comes from the same root as the English word 'butt', as in a large wine cask - derives from their hogshead-like shape, and what stimulated their building was Siena's position on waterless hills, nearly a thousand feet above sea level. The nearest rivers are many miles away and down on the plain, and as the town grew into a burgeoning commercial centre in the early middle ages, this lack of water became a serious problem.

An element of desperation seems to lie behind the early medieval belief that there was an underground torrent somewhere beneath the city, which was dubbed the river Diana. For at least two hundred years from the 12th century onwards, the Sienese government spent large sums on futile excavations in search of the Diana and offered enormous rewards to anyone who could find it. These geomantic excursions, however, almost certainly uncovered some intriguing water systems dating back to Roman times and earlier, contributed to the Senese's tunnelling skills, and to the eventual realization that large quantities of water could be collected from natural seepage through the rock of the higher surrounding hills, if only a means of channeling it could be devised.

In fact, the technology Siena used originated over 2,500 years ago in Iran. Kanats, as they are commonly called, spread throughout the Middle East, and with the Arab conquests were introduced to Spain and thence to the Canary Islands, Mexico and Chile. Many such systems have since fallen into decay, but there are still a considerable number of fully-functioning ones in the Islamic world, and Tehran, for example, was receiving all its water from kanats until 1930.

Standing in the city's scallop-shaped Piazza del Campo beside the brimming basin and gurgling spouts of the the Fontegaia - the Fountain of Joy, so named after the wild popular jubilation it caused when the 'bottini' finally brought plentiful fresh water to the very heart of the hill-top town in 1343 - it is difficult to believe that this sparkling abundance can really be produced by so minimal a source as mere seepage and so simple a means as gravity. But the secret is about to be revealed as a smiling man in jeans and a blue workman's shirt, appears swinging a couple of camping-gaz lamps. This is the 'bottiniere' Franco Bertazzo, now in his forties and the holder for over a decade of what must surely be one of the most ancient, continuously-existent civic posts anywhere.

Franco suggests that, before setting out on our main subterranean mission along the 'bottino maestro' (master bottino), which runs from the Fontegaia the length of the center of town and then under the walls and far out into the countryside, we take a look at a smaller, more ancient 'bottino' of the kind that inspired the much more grandiose medieval system. Crossing the Piazza, we cut through some side streets until we come to the Fontanella (Little Fountain) below the towering, dramatically-buttressed Sant'Agostino church.

Lighting our lamps, we go through a steel door and find ourselves in a weird, glistening passageway. Almost at once the tunnel forks to left and right. Taking the one to the left we stumble along what seems like a naturally-eroded pothole, except that in places it is evident from the hundreds of pick-marks that it has been laboriously carved out of the 'tufo', the sand-colored volcanic rock upon which Siena is built.

But in many places the entire tunnel is thickly encrusted with sugary calcification, which has also produced countless stalactites that hang dripping from the roof. After a couple of hundred yards we emerge at the fork again - for the Fontanella 'bottino' consists of a single loop, not connected to any of the other principal systems. The picturesque calcification, Franco explains, is one of the main enemies of the 'bottini', and why the Fontanella now produces very little running water and has become essentially an historical curiosity.

Returning to the Piazza, we arrive at the spot behind the Fontegaia and the cafe-tables that ring the upper arc of the square where an unobtrusive trap-door opens on to a steep flight of steps into a electrically-lit, brick-vaulted chamber. From here a narrow doorway leads into the 'bottino maestro'. Along the way we encounter the 'gallazoni', a series of tanks. They are a simple, but effective, purification method: as the water flows from one to another over low shelves, the calcium deposits it carries fall gradually to the bottom (the eventually thick flakey crusts this process leaves behind being dug out at regular intervals to keep the tanks clean).

Entering the 'bottino maestro' proper, we make our way into the pitch darkness by the light of our lamps. Sometimes the passage walls are simply of bare 'tufo', but many stretches are lined with beautifully-executed brickwork. There is complete silence, the air smells fresh and remarkably dry. Indeed, the only water is that which is flowing noiselessly down the brick-built central channel. Undisturbed by any wind, the water appears to be absolutely still, but when one bends down and puts one's hand in it, it turns out to be running quickly, the reason, Franco points out, why at intervals we come upon zig-zag sections of the channel, inserted to maintain the consistency of the flow.

One has the sensation that the brick-paving is flat, but in reality it is gently ascending at a finely-graded rate of 1 metre per kilometre. 'Of course, some of the architecture down here is really impressive,' said Franco. 'But what I often find even more astounding is the precision of the mathematical calculations that were required to make the whole system function.'

Secondary tunnels frequently branch off to one side or the other, usually with hand-painted panels on the walls at their entrances giving the names and addresses of families and institutions and maps of the configurations of the subsidiary passageways. These branches lead to private wells. Also noted on the panels are the number of 'dadi', or fractions thereof, each consumer is entitled to receive. 'A 'dado' is the equivalent of a flow of 400 litres of water over 24 hours,' Franco said. The metering of this supply to the scores of different customers is achieved by little gates inserted in the subsidiary channels with different sized holes that regulate the amount of water passing through them. The correctness of the level of supply can be instantly checked by the 'bottiniere' by means of calibrated conical spike - like a jeweller's finger-ring gauge - that gives the measurement of the diameter of each hole.

Whether the water from the 'bottini' - which certainly appears crystal clear - is now safe to drink is a moot point. The 'bottino maestro' passes under the city at an average depth of about 35 feet, and several miles out into the Sienese countryside around 100 feet underground. Once upon a time, the state enforced severe restrictions even on the types of agricultural activity that could be pursued in the vicinity of the 'bottini', but the fear now is that the water could be subject to contamination from fertilizers and pesticides in the soil above.

Along the way, we encounter shafts leading directly from the main artery of the 'bottino maestro' to the surface, called 'occhi' (eyes). The effect of looking up these bore holes at the tiny circle of light of their barred entrances is like peering up the inside of a factory chimney. They were sunk, Franco said, both to check the progress of construction during the mining of the 'bottini' and to carry waste to the surface.

Outside the city walls, however, the 'bottini' are almost entirely sealed off. The Sienese government was acutely aware that their enemies might try to poison the water supply, or secretly to enter the city through the 'bottini', and a number of conspiracies of this nature were uncovered. One of the most notorious was in 1526, when a Florentine plot to penetrate the 'bottini' via a well was exposed after a carpenter reported to the government an order for long ladders, and the chief conspirator was duly beheaded in the Piazza.

The last time the 'bottini' were proposed for use in a clandestine military action was in 1944 when Italian partisans planned to smuggle arms and fighters through them into the centre of town to stage a surprise revolt against the Germans - a scheme only abandoned at the last minute on the decision to make Florence the focus of the uprising.

At the end of a fascinating morning investigating some of the highways and byways of Siena underground, we arrive at a brick stairway leading to the surface near the city walls. Franco unbolts a small metal door which opens out of a wall onto a quiet lane. At this very moment a woman is attempting to back her car in front of the door. Seeing two men climbing out of the side of the wall holding gas lamps aloft, she blinks, shakes her head and drives off at speed without looking back again.

First published: Traveller