Inspired by Orion, the founder of the city, the fountain built in 1547 is the work of Giovanni Angelo Montorsi, a student of Michelangelo. It has a dodecagonal plan and is made of Carrara marble. It extends over three steps on which lie eight sea monsters in black stone, which anticipate the actual source that houses four basins with as many mythological figures representing the rivers Nile, Ebro, Tiber and Camaro. In the center of the basin is a richly decorated marble base, with tritons supporting a basin decorated with marine symbols, and four water lilies supporting a smaller basin with four putti riding on dolphins. Overseeing everything is the statue of Orion with his faithful dog Sirius.