The Greek theatre of Syracuse lies on the south slopes of the Temenite hill, overlooking the modern city of Syracuse. It was first built in the 5th century BC, rebuilt in the 3rd century BC and renovated again in the Roman period. Today, it is a part of the Unesco World Heritage Site of 'Syracuse and the Rocky Necropolis of Pantalica'.
It seems that the theatre was renovated in the third century, transforming it into the form seen today. Its structure was extended, taking into account the shape of the Temenite hill and the best possibilities for acoustics. Another typical characteristic of Greek theatres is the celebration of the panoramic view, also applied to the theatre of Syracuse, offering a view of the bay of the port and the island of Ortygia.
During the Roman era, important modifications were made to the theatre, perhaps at the time when the colonia was founded in the early Augustan period. The cavea was modified to a semicircular form, typical of Roman theatres, rather than the horseshoe used in Greek theatres and corridors allowing access past the scene building (parodoi). The scene building itself was reconstructed in monumental form with rectangular niches at centre and two niches with a semicircular plan on the sides, containing doors to the scene.
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.