Perhaps the most famous fons sacer , where the Romans built a massive temple and bath complex around a naturally hot spring. They identified the local Celtic goddess Sulis with their own Minerva, creating a "syncretic" deity who oversaw the healing waters.

Even the Roman practice of deditio (unconditional surrender) had echoes of the Fons Sacer . A defeated enemy would be brought to a spring or a water source, stripped, and forced to pass under a yoke of spears — a ritual death and rebirth as subjects of Rome.

A central hub where Roman water culture and sanctuaries were integrated into the limes (border) defenses, highlighting how the fons sacer followed the legions across Europe. Rituals of the Sacred Spring

At the spring, a sacred animal was sacrificed. Its entrails were read. Then, the animal’s spirit was invoked. In the most famous tradition, a woodpecker — the bird of Mars — would appear at the spring. The exiles were to follow its flight path. If no bird appeared, a wolf or a bull was released from the spring’s edge; the direction it ran was the path of destiny.