One of the most important churches of Mystras is the Cathedral of Agios Demetrios, built in 1280- 1292. It is the oldest church in the city.
This church has a mixed architectural style: on the one hand it has a three-aisled basilica with a narthex and a bell tower, built in the 13th century on the ground floor, and on the other hand, the upper floor is a cross-in-square church, added in the first half of the 15th century. Its interior is decorated with wall paintings in many different styles. This is where the last Byzantine emperor, Constantinos Paleologos, was crowned in 1449.
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.