The ramparts of Quebec City are the only remaining fortified city walls in North America north of Mexico. The British began refortifying the existing walls, after they took Quebec City from the French in the Battle of the Plains of Abraham in 1759.
The wall, which runs on the eastern extremity on the Promontory of Quebec, surrounds most of Old Quebec, which was declared a World Heritage site by UNESCO in 1985. The fortifications were designated a National Historic Site of Canada in 1948.
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.