The amphitheatre is sited in the most easterly corner of the city, near the Sarno Gate. It was completed in 80BC, having been commissioned by two magistrates, C. Quintus Valgus and M. Porcius. An impressive structure, the amphitheatre measures approximately 135 x 104 meters and could hold about 20000 people. It is the earliest surviving permanent amphitheatre in Italy, and is therefore particularly important in providing a picture of this type of typically Roman architecture.