Known already to the Romans, the Baths of San Filippo are situated in an area of great naturalist and scenic interest, famous in particular for its numerous monumental trees. The Baths were rebuilt in 1566 at the initiative of Cosimo I de' Medici. They were frequented by other illustrious members of the Medici family, such as Lorenzo the Magnificent, who stayed there in 1485, and Grand Duke Ferdinand II, who visited the baths in 1635, in the attempt to rid himself of a persistent headache.

In the late 18th century Giorgio Santi performed the first chemical analysis of the waters. In the 19th century, Antonio Targioni Tozzetti made a thorough study of the waters, while Giuseppe Giuli, after having described their chemical properties, evaluated their therapeutic effects.

The Baths of San Filippo are linked not only to the subject of medical hydrology, but also to the relationship between art, science and technology. The water contains, in fact, abundant amounts of calcium carbonate, which, in solidifying, form singular white concretions. Already in the 13th century Ristoro d'Arezzo, in his Composizione del Mondo (Composition of the World), had pointed out the singular nature of this kind of water: "And there had risen mountains, which were all white, almost like snow, made of water that had become stone; and the sign of this was that the water springs from the top of those mountains, and in flowing down and spreading around those mountains, that water is transformed into stone, causing the mountain to grow continuously. And at the top of one of those mountains was a bath of hot water; in which we bathed and our hair, which was in the water, spread out like stone all around, like wax around the wick to make a candle." The water's cementation property was utilised, toward the middle of 18th century, by Leonardo De Vegni, who invented a technique, known as "plastica dei tartari", with with he managed to make various kinds of artistic objects. In 1766, to produce these objects, De Vegni set up a special workshop, highly appreciated by Duke Peter Leopold. In 1788 he presented to the Accademia dei Fisiocritici of Siena a "Memorandum on the Plastica de' Tartari", in which he described in every detail his highly original method. "Without the aid of a chisel, or any similar tool," noted Leonardo De Vegni, "I obtain, almost immediately from the water, bas-reliefs of any size, and of the finest carving desired, as white, glossy and hard as I wish, being able to have them all of that consistency which we have noted above. And undoubtedly I can extend this invention to architectural decorations, memorial stones, basins for fountains and garden vases of rustic workmanship, and such, as resistant as marble to weathering." Emanuele Repetti too, in his Dictionary, described the method invented by Da Vegni: "We owe to the engineer Leonardo Vegni the industrious method of filling with the encrustations of the S. Filippo thermal waters the concave forms displayed there; and this by dripping the water from cross-boards suspended high above the ground. Around this apparatus are hung those forms that are to receive the spray of water, so that very fine molecules of white tartar are deposited on them. The operation may be either slow or fast, depending on how far or how near the object is brought to the falling water, so that a greater or lesser amount of calcium carbonate is deposited on it."

Today the Baths of San Filippo, with their modern facilities, are the ideal place for a relaxing vacation and offer, thanks to the curative properties of their waters, a valid remedy for various disorders.