The Vastseliina Castle was a castle of the Livonian Order, Bishopric of Dorpat. It was constructed in 1342 by the Landmeister Burkhard von Dreileben as part of the border fortifications of Old Livonia against Novgorod, Pskov and later Moscow. In the Middle Ages, Vastseliina Castle was well known in the Catholic world as a popular destination for pilgrims. They worshipped the holy cross in the castle chapel and a visit to the chapel gave them sanctification for 40 days – it was first validated by Pope Innocentius VI in 1354.
The castle met its end during the Great Northern War when it was demolished by Russian troops (1702). Today the ruins are open to the public.
Reference: Wikipedia, VisitEstonia
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.