At about 40m long, Carlungie Earth House is one of the largest and most complex examples of its kind in Scotland. It was accidentally discovered during ploughing in 1949. Subsequent excavations during the following two years also revealed about eight associated stone dwellings at ground level.
Earth houses, or souterrains as they are also known, were not dwellings, but stone-lined underground passages which typically date to the Iron Age. They’re found along much of eastern Scotland, as well as in Ireland, Cornwall and Brittany.
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.