They were built during the 3rd century after J.C. Cimiez was then Cemenelum.
Several thousands of people could sit here. Like the Coliseum in Roma, a large canopy (velum) could be stretched above them to protect the audience from the sun. You can still see the places where the masts were erected to support the velum.
They are located next to the baths and the Roman public shows used to take place here.
The ruins are 70m long (the arena have the shape of an ellipse). Until 2011, the Nice Jazz festival took place here.
You can freely enter the arena. They are located at the crossroad of the "avenue de Cimiez" and the "avenue des arènes de Cimiez", next to the Roman archeology museum , the Matisse museum and a nice park.
It is fairly easy to park your car in the vicinity. A free parking is located avenue du Monastère de Cimiez along the park. On-street parking in this area is free.