Skenfrith Castle was established by the Normans in the wake of the invasion of England in 1066, to protect the route from Wales to Hereford. Possibly commissioned by William fitz Osbern, the Earl of Hereford, the castle comprised earthworks with timber defences. In 1135, a major Welsh revolt took place and in response King Stephen brought together Skenfrith Castle and its sister fortifications of Grosmont and White Castle to form a lordship known as the 'Three Castles', which continued to play a role in defending the region from Welsh attack for several centuries.
At the end of the 12th century, Skenfrith was rebuilt in stone. In 1201, King John gave the castle to a powerful royal official, Hubert de Burgh. During the course of the next few decades, it passed back and forth between several owners, including Hubert, the rival de Braose family, and the Crown. Hubert levelled the old castle and built a new rectangular fortification with round towers and a circular keep. In 1267 it was granted to Edmund, the Earl of Lancaster, and remained in the hands of the earldom, and later duchy, of Lancaster until 1825.
Edward I's conquest of Wales in 1282 removed much of Skenfrith Castle's military utility, and by the 16th century it had fallen into disuse and ruin. The castle was placed into the care of the state by the National Trust in 1936, and is now managed by the Cadw heritage agency.
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.