Birtvisi is a ruined medieval fortress in Kvemo Kartli, Georgia, nested within limestone cliffs in the Algeti river gorge. It is now within the boundaries of the Tetri-Tsqaro municipality, adjacent to the Algeti National Park.
Birtvisi is essentially a natural rocky fortress of 1 km², secured by walls and towers, the most prominent of which – known as Sheupovari ('Obstinate') – tops the tallest rock in the area. Various accessory structures, an aqueduct included, have also survived.
In written sources, Birtvisi is first mentioned as a possession of the Arab amir of Tiflis of which he was divested by the Georgian nobles Liparit, Duke of Kldekari and Ivane Abazasdze in 1038. In medieval Georgia, Birtvisi entertained a reputation of an impregnable stronghold whose master could control the entire strategic Algeti gorge. The Turco-Mongol amir Timur notably reduced the fortress during one of his invasions of Georgia in 1403. After the partition of the Kingdom of Georgia later in the 15th century, Birtvisi was within the borders of the Kingdom of Kartli and in possession of the princes Baratashvili.
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.