The Amphitheatre of Mérida is situated in the Roman colony of Emerita Augusta, present-day Mérida, in Spain. The city itself, Emerita Augusta, was founded in 25 BC by Augustus, to resettle emeritus soldiers discharged from the Roman army from two veteran legions of the Cantabrian Wars (the Legio V Alaudae and Legio X Gemina). The amphitheatre itself was completed in 8 BC. The term emeritus refers to the soldiers, all of whom had been honorably discharged from service.
The amphitheatre had a capacity of approximately 15,000 spectators and had supporting stairs and hallways (scalae) that connected the different parts internally.
The amphitheatre is part of the Archaeological Ensemble of Mérida, which is one of the largest and most extensive archaeological sites in Spain. It was declared a World Heritage Site by UNESCO in 1993.
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.