At Bagni San Filippo, a few kilometres from Siena, immense white formations emerge from the forest. They are composed primarily of travertine, a limestone rock born from a slow dialogue between water, stone, and time.

Here, hot thermal waters rise from deep within the earth, carrying calcium and bicarbonates. When they reach the open air, they gradually release carbon dioxide. Calcium carbonate then precipitates, layer upon layer, year after year, transforming the passage of water into mineral matter.

From this process emerge astonishing forms: the Balena Bianca, the “White Whale,” an immense limestone formation that seems to have washed ashore in the heart of the vegetation; waterfalls frozen in motion; and natural pools whose edges are gradually covered with a delicate white lace of mineral deposits.

The springs of Bagni San Filippo are also sulphurous. Their distinctive smell is a reminder of the presence of sulphur, while the water contains, among other minerals, calcium, magnesium, and sulphates. At the bottom of the pools, mineral-rich muds form naturally and have long been associated with thermal bathing traditions and skin treatments.