Mount Fokas is a 862m high hill in in the area of Corinth. A medieval settlement existed on its trapezoid summit and later a castle was built by the Franks in the 13th century (or perhaps by the Byzantines, a little earlier).
The castle controlled the plains of Nemea and the main route to the center of Peloponnese. It had visual contact with other Frankish castles in the area like Acrocorinth or Agios Vasilios but also with some castles in Central Greece, on the opposite side of the gulf of Corinth.
Only a few ruins of the walls and from the settlement remain at the lower part of the rock.
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.