The Roman amphitheatre in Brescia is located immediately at east of the Capitolium. It has been built in the Flavian era and altered in the 3rd century. With its 86 meters diameter, is one of the largest Roman theatres in northern Italy and originally it housed around 15,000 spectators.
In the 5th century, an earthquake has heavily damaged the building. In addition, in later centuries, its remains were incorporated into new buildings built on top of it, largely demolished starting from the 19th century. Of the original structure are preserved the semicircular perimeter walls, the two side passages (aditus) and the remains of the proscenium, as well as many fragments of columns and friezes of the scaenae frons. The most of the orchestra and the ima cavea are still below ground. The archaeological excavations should resume in the coming years.
References:The ancient Argos Theater was built in 320 BC. and is located in Argos, Greece against Larissa Hill. Nearby from this site is Agora, Roman Odeon, and the Baths of Argos. The theater is one of the largest architectural developments in Greece and was renovated in ca 120 AD.
The Hellenistic theater at Argos is cut into the hillside of the Larisa, with 90 steps up a steep incline, forming a narrow rectilinear cavea. Among the largest theaters in Greece, it held about 20,000 spectators and is divided by two landings into three horizontal sections. Staircases further divide the cavea into four cunei, corresponding to the tribes of Argos A high wall was erected to prevent unauthorized access into the theatron and may have helped the acoustics, but it is said the sound quality is still very good today.
Around 120 CE, both theaters were renovated in the Roman style.