📜 Ancient wellspring in Tonnerre, France, built into a haunting grotto since Roman times. 🔍 A Vaucluse spring with a varied but perpetual flow, converted into a washhouse in 1758. Its origin remains a mystery, explored to 61m depth. # Why Go 🌊 Mysterious natural spring with varied flow, its origin still a secret. 🏛️ Historic Roman and medieval constructions. 📸 Picturesque grotto, tranquil and evocative, with crumbling masonry and moss. 🚶 Easy access for self-guided tours available all year. # Why Avoid ⚠️ Diving access is restricted due to past fatalities. # Tips ☀️ Water flow is gentle in summer, more vigorous in spring due to snow melt. 🗣️ Staff speak French, English, and Spanish for group visits. 🐾 Pets are welcome. # Cost 💰 Free self-guided visits. # Hours 🕒 Self-guided tours: all year round. Group visits: by prior arrangement.