St. Gereon's Basilica (Basilika Sankt Gereon) was first mentioned in 612. However, the building of the choir gallery, apse, and transepts occurred later, beginning under Archbishop Arnold II von Wied in 1151 and ending in 1227. It is one of twelve great churches in Cologne that were built in the Romanesque style.
St. Gereon has a highly irregular plan, the nave being covered by a decagonal oval dome, 21.0 m long and 16.9 m wide, completed in 1227 on the remains of Roman walls, which are still visible. It is the largest dome built in the West between the erection of the Hagia Sophia in the 6th century and the Duomo of Florence in the 15th century.
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.