This semicircular structure with its rows of arches is a theatre from the time of the emperor , and it has lived at least three more lives since then.
It was finished around 13 BC and named after , the emperor's nephew and son-in-law, who died young. About fifteen thousand spectators could fit inside, and it became the model for later theatres across the empire, the Colosseum among them.
Once the performances stopped it became a quarry, then a fortress held by noble Roman families, and in the sixteenth century the built a residential palace on top of it. That palace is still standing, and the upper floors today hold ordinary apartments, which means people live here inside a building two thousand years old.
The arches at street level sit a few metres below the road, because the city around it was raised over time while the theatre kept sinking into its own foundations.
From here it's a five-minute walk back to Piazza Mattei. We take Via Montanara and keep to the left, and the fountain appears in front of us again.
Sources. Story: Sovrintendenza Capitolina ai Beni Culturali (Teatro di Marcello); Treccani (Marco Claudio Marcello) Photos: Photo: Vadim Zhivotovsky (Wikimedia Commons, CC BY 3.0)
