A fascinating story concerns the underground of Siena. Underneath the city Dante, in the Divine Comedy, claims that Diana, a river that has never been found, flows. Beneath the city of Siena are the Bottini, 25 kilometers of tunnels dug into the tuff since Roman times. The Bottini are a masterpiece of hydraulic engineering for the knowledge of the time.The term "buctinus" probably for the "barrel" vault, appears for the first time in a document of 1226 and gives origin to the name BOTTINI, as they are still called today, by all the Sienese, the underground aqueducts. There are two main branches of the bottini, the oldest one, the Bottino maestro di Fontebranda, which is located at a considerable depth and carries water from Fontebecci to Fontebranda, and the Bottino maestro di Fonte Gaia, built around 1300, which feeds the fountain of Piazza del Campo, Fonte Gaia and with the overflow, also other minor fountains.
The more adventurous can descend into the Bottini thanks to an association that organizes guided tours.
