But, from where is the water collected, and most importantly, how is it brought to the fountains?

"In Siena people have always used the word bottini to denote the underground aqueducts, excavated in the tufa, partially walled, almost all passable, that after having collected the seepage from rainwater and from springs in the surrounding hills, supply the public fountains and many private wells with this water. . . ."
--Fabio Bargagli-Petrucci, Le fonti di Siena e i loro acquedotti.

One finds the term Buctinus cited in documents for the first time in 1226 where it refers to the shape of the ceilings, volte a botte, or barrel vaulted, in almost all the bottini (only the bottino of Fontanella, probably of Etruscan origin, has "tent vaults," ceilings shaped like an inverted "V"). One recognizes two methods of excavation the tunnels: in the case of the bottino of Fontebranda, the oldest, it was dug from only one end, that is from the Fountain, rising on a gradual incline, always staying between the two geologic strata that form the Sienese hills: the aquifer above, of porous and permeable yellow sand (a type of Pliocene limestone), that filters the rainwater; the aquiclude below, of compacted and impermeable deep blue clay that acts as a barrier to the water. The water thus collected runs on the bottom of the tunnel in a little channel called a gorello over terra cotta tiles, gaining in volume and reaching the fountain with an abundant flow.

For the bottino of Fonte Gaia the excavation began instead from two points: Fonte Gaia and Santa Petronilla (one of the sources north of Porta Camollia), in the same direction converging on the mid-point, and also from Santa Petronilla, to the North toward Fonte Becci. This method was faster but also more difficult because it was possible that the two tunnels would not meet, but instead pass by each other in different planes. One can see where this has happened in sections that are taller or wider than normal. To maintain a certain direction, in absence of adequate instruments, every so often the workers would excavate vertical shafts from which they could adjust the alignment. These well shafts, called "eyes," also served to ventilate the tunnels and permitted the workers to haul the spoils of excavation to the surface.

The work in the bottini

The route of the bottini

The history of the bottino of Fonte Gaia

The situation today

Those who have more specific interests in historical dates or in texts which contain more precise details may wish to consult these links:

Historical Chronology

Bibliography