When Michelangelo, in 1536, created what is now known as the Fountain of the Goddess Roma in the Piazza del Campidoglio he was just making a beautiful ornament to this square.
At the time the flow of water from Rome’s aqueducts did not reach the Capitoline Hill yet and it was not until 1588 that Matteo Bartolani won a competition that allowed him to change the construction into a fountain.
At the time the structure was known as “Senate Steps” or “Pallas Kidnapped”. Initially there was a huge statue of Minerva in the central niche, which was replaced with the present one of the Goddess Roma.
The two statues on either side of the niche represent the rivers Nile and Tigris, which were taken from the Baths of Constantine on the Quirinal Hill. The tiger representing the Tigris was later changed into the wolf with Romulus and Remus symbolizing Rome’s own river Tiber.
The colossal statue of Minerva itself can now be admired in the courtyard of the Capitoline Museums.
Note that there is another fountain dedicated to the Goddess Roma in the Piazza del Popolo.