This is also a thermal site located a bit farther away, but we mention it because it is truly unique and the trip is well worth your time. Like the Cascate del Molino in Saturnia, we are not talking about artificial pools inside a wellness center, but a place entirely shaped by nature, where bathing is free of charge. Here too, if you wish, there is a hotel with a paid spa, boasting the oldest thermal pool in the province of Siena, open to the public from March to October every day except Tuesday… But this is certainly not the main attraction.
The natural thermae consist of a series of very hot thermal springs that flow into a small cold river, the Fosso Bianco, which over the centuries has created truly incredible limestone formations. These form waterfalls and small pools – some carved out over centuries by local inhabitants – along a path that makes them all easily accessible, in a walk of rare beauty through the forest. The first pools are shallow and less warm; continuing on, you reach an impressive calcium carbonate formation, built up and fed by thermal water that still gushes from its summit, called the “Balena Bianca” (“White Whale”) because it resembles an open whale’s mouth with visible baleen. Here, the water emerges at 48°C and meets the cold river water, creating a fascinating contrast both for bathing and for the white-turquoise color that the thermal stream takes on. Further along the river, you’ll find other natural pools that make up the true Fosso Bianco, at the end of which is the paid wellness center. The pools have different temperatures, depending on whether the hot spring is right there or if the natural pool collects the water from the upper basins. So, depending on the outside temperature, you’ll be spoiled for choice! In some sections of the riverbed, you can also enjoy the therapeutic muds, traditionally used by locals to nourish and smooth the skin.
At Bagni San Filippo, there is also another natural thermal basin: the one at the former furnace. The old industrial buildings are still visible, in front of which white limestone terraces form thermal pools and offer white muds with which you can play in countless ways. Here too, access is free all year round and 24 hours a day, and parking is also free. The water is very hot, even hotter than at Fosso Bianco, making this place a very fun destination even in the middle of winter.
The thermae are located in the province of Siena, in the beautiful Val D’Orcia, which is also home to many locations chosen for filming Ridley Scott’s Gladiator. This is a region of gentle hills dotted with one beautiful medieval village after another, such as Castiglione d’Orcia or San Quirico D’Orcia, both about twenty minutes from Fosso Bianco, but also the famous Pienza (known for its wines and a truly special pecorino cheese), or the evocative Bagno Vignoni with its incredible Piazza delle Sorgenti, also called the Vascone: a large 16th-century rectangular pool that collects a hot, steaming thermal spring right in the center of the medieval village (not suitable for bathing). Or the well-known Montalcino, at the heart of one of Italy’s best red wine regions. Fosso Bianco is also quite close to the wonderful Abbey of Sant’Antimo, one of the most evocative sites in the Monte Amiata area, and together with a dinner in one of the many incredible local restaurants, can make for an unforgettable day trip.
Fosso Bianco
via S. Filippo, Bagni San Filippo (Siena)
Park along the road and then walk down towards the woods and the stream.
https://maps.app.goo.gl/qLQKPz36Xtven3uHA
The former furnace
via del Bollore, Bagni San Filippo (Siena)
Park along the road and then walk on the right.
https://maps.app.goo.gl/qeZbYBZFtZkjfGxW8
