The erroneously named Temple of Minerva Medica is, in fact, a ruined nymphaeum of Imperial Rome, built in the 4th century. Nymphaeum is a building devoted to the nymphs and often connected to the water supply. The decagonal structure in opus latericium is relatively well preserved, the full dome having collapsed only in 1828. It is surrounded on three sides with other chambers added at a later date. There is no mention of it in ancient literature or inscriptions.
The structure represents a transition in Roman secular architecture between the octagonal dining room of the Domus Aurea and the dome of the Pantheon, in particular, and the architecture of nearby Byzantine churches. The diameter of the hall is about 24 metres, and the height was 33 — important from the structural point of view, especially for the ribs in the dome. In the interior are nine niches, besides the entrance; and above these are ten corresponding round-arched windows. Both the interior and exterior walls were once covered with marble.
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.