Piazza Navona is a square in Rome, Italy. It is built on the site of the Stadium of Domitian, built in the 1st century AD, and follows the form of the open space of the stadium. The ancient Romans went there to watch the agones, and hence it was known as "Circus Agonalis"
Interesting Piazza Navona Facts: Pope Innocent X started a tradition of covering the drains of the three fountains on Saturdays and Sundays in the 1600s, to allow people to enjoy the pooled water. ... In the center of Piazza Navona is the Fountain of the Four Rivers, with an Egyptian obelisk.