Piazza Navona Underground & The Stadium of Domitian
There is little big surprise underneath the Piazza Navona. If you have a good look at the shape of this Piazza you might notice it must have been some kind of arena in the old days. Well it has, the square was built upon the Stadium of Domitian, which still can be visited underground of the square. You can choose to buy tickets with or without guidance.
Open daily from 10-19h (saturday till 20h).